What affects the bus frequency. Processors. New serial buses

However, it did not arouse much interest and was lightly criticized. The author took into account the comments, modified and supplemented the article, so now you are reading the updated version.

The purpose of the article is to determine the effect of the processor system bus frequency and memory parameters on performance. Particular attention is paid to the performance dip at 183 MHz and the Active Precharge Delay memory parameter.

Maternal aSUS board The A7N8X-X has some specific "quirks" that prevent it from being generalized to all nForce2 boards. However, the general conclusions apply to most other motherboards.

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• Processor - AMD Athlon 1700+ Thoroughbred-B. Maximum overclocking - 2200 MHz at 1.85 V.
• Memory - PC3200, 1x512 MB, 5-2-2-2.5, Nanya. Works in sync with the processor.
• Motherboard - nForce2 400, ASUS A7N8X-X, BIOS 1007. CPU Interface \u003d Optimal (locked in this firmware). Bus Disconnect \u003d off. The maximum overclocking is 208 MHz.
• Video card - Radeon 9000, 64 MB, 128 bit.
• Hard drive - WD400JB.
• Operating system - MS Windows 2000 SP4.

The motherboard is no different from the A7N8X except for single-channel and no additional controllers. They even have numbers bIOS firmware and the changes made are the same. The difference in performance with a two-channel system, in most cases, is within a few percent. A good article on the performance impact of dual-channel is http://www.lostcircuits.com/motherboard/asus_a7n8x-x/.

What tests were used?

Obviously, the performance drop at 183 MHz is not related to the processor. Therefore, programs were used that intensively work with large amounts of data and heavily load the memory subsystem. Two archivers were chosen: 7-zip (LZMA algorithm) and RKC (PPM algorithm). The file size for compression is 20 MB. Peak use random access memory for RKC - 400 MB, for 7-zip - 200 MB. In 7-zip, the processor plays a big role in increasing the word size, so the tests were performed at 255 and 64 words.

Throughout the development of the entire human race, stones have been our integral companions. Axes, arrowheads ... pyramids in the end! Silicon alone is worth it - because it was thanks to it that we got fire. Even if not so long ago, but already in the name of the development of the computer industry in the "bronze" age, people decided to torment their "stones" again. How it all began, we are even afraid to think. Either since the ancient Z80, or later, on the 286/386 series of processors, at some point a certain group of people discovered a new fascinating occupation, or rather, became the founder of a new direction - overclocking... The word, in fact, is not ours, it is translated from English as "promotion". Our definition has taken on a slightly different form - acceleration, that is, increased productivity. We will tell you about what it is and how it happens in this article.

How did it start

In those glorious years, when prices for computer components literally went off scale, processors were not easy to overclock. If now overclocking the computer is practically no problem - the presence of a keyboard and the corresponding software allow you to do this in literally a few minutes - then the clock frequency was increased with the use of a soldering iron, rearranging the jumpers and closing the legs of the processors. That is, at that time overclocking was available only to a select few - brave, selfless and experienced techies.

But not only processors were overclocked. Graphics cards and RAM were next, and more recently, enthusiasts have made improvements to optical mouse performance.

Why is this necessary?

And, in fact, why are we going to do something? Let's add up all the pros and cons, in order to understand, do we really need it? The pluses include the following points:

• Increased productivity has never bothered anyone. Its increasing amount cannot be accurately predicted, it all depends on the components used. For example, the gain from overclocking the processor with a powerful video card almost always increases the speed in 3D applications. Although, without even aiming to improve performance in games, the productivity of the computer in general will extend to archiving, transcoding, video / sound editing, arithmetic calculations and other useful operations. But from "tuning" the memory, the gain, most likely, will not be as great as from overclocking the processor or video card.
• Many of the concepts that you will become familiar with in the overclocking process will provide invaluable experience.

And here is the other side of the coin:

• There is a risk of destroying the equipment. Although it depends on your hands, the quality of the components used and, finally, the ability to stop.
• Reducing the life of overclocked components. Here, alas, there is nothing to be done: with increased voltage and a rather strong frequency, coupled with poor cooling, the service life of the "iron" can be halved. This may seem unacceptable to many, but there is one detail: on average, the life of a modern processor is ten years or more. Whether it is a lot or a little, everyone decides for himself. We just remind you that as of today, progress has reached such a rate of development that a processor released two or three years ago is already considered impermissibly outdated. What can we say about five ...

Basic concepts

Having designed a processor, the manufacturer creates a whole series (line) with its various characteristics, and often based on one single processor. Why, you tell me, do the frequencies differ on two identical processors? Do you think that the company that produces them manages to program each processor at a specific frequency? There is, of course, another way. The frequency of the junior processors of the line can easily reach even the older ones, moreover, sometimes exceeding it. But hidden problems lie in wait on all sides, one of which is the question of the successful selection of the "stone" ... but this is another story, which we will tell you about next time. Because for further study of the material, it is necessary to familiarize yourself with all the terms that one way or another will appear in the text.

BIOS (Basic Input-Output System) - Elementary input / output system. In fact, it is an intermediary between the hardware and software environments of the computer. More specifically, it is a small configuration program containing settings for all the "hardware" content of your computer. You can make your own changes to the settings: for example, change the processor frequency. The BIOS itself resides on a separate flash chip directly on the motherboard.

FSB (Front Side Bus) - The system or processor bus is the main channel providing communication between the processor and other devices in the system. The system bus is also the basis for shaping the frequency of other computer data transfer buses, such as AGP, PCI, PCI-E, Serial-ATA, as well as RAM. It is she who serves as the main tool in increasing the frequency of the CPU (processor). The processor bus frequency is multiplied by the processor factor (CPU Multiplier) and provides the processor frequency.

Beginning with Pentium 4, corporation Intel began to apply technology QPB (Quad Pumped Bus) - she QDR (Quad Data Rate) - the essence of which is the transfer of four 64-bit data blocks per processor cycle, i.e. with a real frequency, for example, 200Mhz we get 800Mhz effective.

At the same time, the once competing AMD Athlon transmission occurs on both signal edges, as a result, the effective transfer rate is twice as high as the real frequency, 166Mhz for Athlon XP gives 333 effective megahertz.

The situation is approximately the same in the line of processors from AMD - K8, (Opteron, Athlon 64, Sempron (S754 / 939 / AM2)): the FSB has been continued, now it is only a reference frequency (clock generator - HTT), multiplying by a special multiplier we get the effective frequency of data exchange between the processor and external devices... The technology was named Hyper Transport - HT and is a special high-speed serial links with a clock frequency of 1 GHz at "doubled" data rate (DDR), consisting of two unidirectional buses 16-bit wide. Maximum speed data transfer rate is 4 Gbps. Also, the clock generator generates the frequency of the processor, AGP, PCI, PCI-E, Serial-ATA. The memory frequency is derived from the processor frequency, thanks to the derating factor.

Jumper is a kind of "contact closure" assembled in a miniature case. Depending on which contacts on the board are closed (or which are not closed), the system determines its own parameters.

CPU

CPU multiplier (Frequency Ratio / Multiplier) allows us to achieve the final processor frequency we need, while leaving the system bus frequency unchanged. Currently, all Intel and AMD processors (except Athlon 64 FX, Intel Pentium XE and Core 2 Xtreme) the multiplier is locked, at least upwards.

CPU cache (cache) is a small amount of very fast memory built directly into the processor. The cache has a significant impact on the speed of information processing, since it stores data that is currently executing, and even those that may be needed in the near future (this is controlled by the data prefetch block in the processor). There are two levels of cache and is designated as follows:

L1 - cache of the first level, the fastest and least capacious of all levels, directly "communicates" with the processor core and most often has a split structure: one half for data ( L1D), the second - instructions ( L1I). Typical capacity for AMD S462 (A) and S754 / 939/940 processors is 128Kb, Intel S478 \\ LGA775 - 16Kb.

L2 - the cache of the second level, which contains data preempted from the cache of the first level, is less fast, but more capacious. Typical values \u200b\u200bare 256, 512, 1024 and 2048Kb.

L3 - was used in desktop processors for the first time in the Intel Pentium 4 Extreme Edition (Gallatin) processor and had a capacity of 2048Kb. Also, for quite some time, I found a place for myself in server CPUs, and should soon appear in a new generation aMD processors K10.

Core - silicon chip, a crystal consisting of tens of millions of transistors. He, in fact, is a processor - it is engaged in the execution of instructions and processing the data coming to it.

Processor stepping - a new version, generation of processor with modified characteristics. Judging by the statistics, the higher the stepping, the better the processor overclocks, although not always.

Instruction sets - MMX, 3DNow !, SSE, SSE2, SSE3, etc. Since 1997, with the introduction of the first ever MMX (MultiMedia eXtensions) instruction by Intel, overclockers have received yet another way to increase performance. These instructions are nothing more than the concept of SIMD (Single Instruction Many Data) and allow no less processing of multiple data items with a single instruction. By themselves, of course, they will not increase the speed of information processing, but with the support of these instructions by programs, a certain increase is noted.

Technical process (manufacturing technology) - along with various optimizations carried out with each new stepping, process reduction is the most in an efficient way overclocking the processor. It is designated by a strange combination of letters "um", "nm". Example: 0.13 \\ 0.09 \\ 0.065μm or 130 \\ 90 \\ 65nm.

Socket (Socket) - The type of processor socket for installing the processor in the motherboard. For example, S462 \\ 478 \\ 479 \\ 604 \\ 754 \\ 775 \\ 939 \\ 940 \\ AM2, etc.

Sometimes manufacturing campaigns, along with the numerical name, use alphabetic ones, for example S775 - aka Socket T, S462 - Socket A. Such visible confusion can disorient a novice user a little. Be careful.

Memory

SDRAM (Synchronous Dynamic Random Access Memory) - synchronization system dynamic memory with random access. TO this type refers to all the RAM used in modern desktop computers.

DDR SDRAM (Double Data Rate SDRAM) - An advanced type of SDR SDRAM with twice the amount of data transmitted per clock.

DDR2 SDRAM - further development DDR, which allows to achieve twice the frequency of the external data bus in comparison with the frequency of DDR chips with the same internal frequency of their functioning. All I / O control logic operates at half the baud rate, which means the effective frequency is twice the real one. Manufactured using a thinner 90nm process technology and along with a reduced rated voltage up to 1.8V (from 2.5V for DDR) consumes less power.

Real and effective memory frequency - with the advent of DDR and DDR2 memory, such a concept as a real frequency has entered our life - this is the frequency at which these modules operate. The effective frequency is the one at which the memory operates according to the specifications of the DDR, DDR2 and others standards. That is, with twice the amount of data transmitted per clock cycle. For example: at a real frequency of DDR 200Mhz, the effective frequency is 400Mhz. Therefore, in the designations it is most often listed as DDR400. This focus can be considered nothing more than a marketing ploy. Thus, we are given to understand that since twice as much data is transmitted per cycle, it means that the speed is twice as high ... which is far from the case. But for us this is not so important, we should not go deep into the jungle of marketing.

Designation of memory by theoretical bandwidth - when buying memory along with familiar designations like DDR 400 or DDR2 800, in our case you can see such names as PC-3200 and PC2-6400. All this is nothing more than the designation of the same memory (DDR 400 and DDR2 800, respectively), but only in theoretical bandwidth indicated in Mb \\ s. Another marketing ploy.

Memory designation by access time - the time during which information is read from the memory cell. It is indicated in "ns" (nanoseconds). In order to convert these values \u200b\u200binto frequency, 1000 should be divided by the number of these same nanoseconds. Thus, you can get the real frequency of the RAM.

Timings - delays arising from operations with the contents of memory cells, given below. This is by no means all of their number, but only the most basic ones:

• CAS # Latency (tCL) - the period between the read command and the start of data transfer.
• tRAS (ACTIVE to PRECHARGE command) - the minimum time between the activation command and the command to close one memory bank.
• tRCD (ACTIVE to READ or WRITE delay) - the minimum time between the activation command and the read / write command.
• tRP (PRECHARGE command period) - minimum time between the command to close and reactivate one memory bank.
• Command rate (Command Rate: 1T / 2T) - command interface delays due to a large number of physical memory banks. Manual setting lends itself so far only to non-Intel chipsets.
• SPD (Serial Presence Detect) is a chip located on a RAM module. It contains information about the frequency, timings, as well as the manufacturer and date of manufacture of this module.

Theory

Exactly how we will exceed the nominal processor frequency, you guessed it, right? Everything is as simple as a donut: we have a system bus (aka FSB or clock generator - for AMD K8) and a processor multiplier (aka multiplier). We simply change the numerical values \u200b\u200bof one of them and at the output we get the required frequency.

For example: we have a certain processor with a standard frequency of 2200MHz. We start to think, why was the manufacturer so greedy when in the same line with the same core there are models with 2600MHz and higher? We need to fix this matter! There are two ways: change the processor bus frequency or change the processor multiplier. But to begin with, if you do not even have basic knowledge of computer technology and are not able to determine the standard FSB frequency or its multiplier from the processor name alone, I advise you to use a more reliable method. Especially for this, there are programs that allow you to get exhaustive information on your processor. CPU-Z is the leader in its segment, but there are others. You can just as well use SiSoftware. Sandra, RightMark CPU Clock Utility. Using the obtained programs, we can easily calculate the FSB frequency and the processor multiplier (and at the same time a lot of previously unknown, but damn useful information).

Take for example intel processor Pentium 2.66GHz (20x133MHz) based on Northwood core.

After some simple operations in the form of raising the FSB frequency, we get 3420MHz.

That's how it is! We already see how in your minds twisted convolutions, multiplying unthinkable numbers by monstrous coefficients ... not so quickly friends! Yes, you understood everything perfectly: for overclocking, we need either an increase in the multiplier or the system bus frequency (and best of all, right away, and, most importantly, more - approx. Hidden internal greed). But not everything is so simple in our life, there are enough sticks in the wheels, so let's get acquainted with them before starting.

You already know that most of the processors on the market have a locked multiplier ... well, at least in the direction we would like - upward. Only happy owners of AMD Athlon 64 FX and some Pentium XE models have this opportunity. (Variants with rare Athlon XP, released before 2003, are not considered). These models can drive their already "non-low-frequency" "stones" practically without problems (fiddling with memory and insufficient FSB frequency reserve on the motherboard). The unlocked multiplier in this series of processors is nothing more than a gift to users who have given a lot of money. Everyone else who is not able to spend $ 1000 on a processor should go (no, not by any means a forest) just another way ...

Increase the FSB or clock frequency. Yes, this is our savior, which in almost 90% of cases is the main overclocking tool. Depending on how long ago you purchased your processor or motherboard, your standard FSB frequency will vary.

Starting with the first Athlons from AMD and Intel Pentium on the S478, the 100MHz system bus was the standard. Then the Athlones switched first to 133, then to 166 and finally ended their lives on a 200Mhz tire. Intel did not sleep either and gradually increased the frequencies: 133, then 200 at once, now 266, and even 333MHz (1333Mhz in QDR terms).

That is, having a modern motherboard with a good potential to increase the frequency of the clock generator (in fact, this quartz that controls the FSB frequency can also be referred to as PLL), everything becomes extremely simple - this is an increase in the frequency itself. To what extent and how to actually change it, we will talk a little later.

We hope you haven't forgotten what FSB is? No, this does not mean the megahertz on which it works, but the immediate meaning. FSB is the system bus that links the processor to other devices in the system. But at the same time, it is the basis for shaping the frequency of other buses, such as AGP, PCI, S-ATA, as well as RAM. And what does that mean? This means that when you increase it, we will automatically increase the frequencies of AGP, PCI, S-ATA and "RAM". And if raising the latter within reasonable limits only plays into our hands (at present, only motherboards based on the NVIDIA nForce4 SLI Intel Edition chipset are able to overclock the processor regardless of memory), then S-ATA, PCI and AGP with PCI-E are completely not necessary. The fact is that they are quite sensitive to such experiments and respond to us with very unpleasant consequences. The ratings of these buses are: PCI - 33.3Mhz, AGP - 66.6Mhz, SATA and PCI-E - 100Mhz. And it is highly discouraged to exceed them significantly. Unstable operation of the same S-ATA can lead to data loss from your S-ATA drive!

That is, this is a very significant limitation ... it was. But the point is this: realizing the benefits of such a miscalculation, some chipset manufacturers decided to fix this problem on their own. It all started with the use of special dividers that automatically switch PCI and AGP buses to their nominal values \u200b\u200bat 100, 133, 166 ... MHz. (and there were such interesting situations in which the processor was stable at 166Mhz, initially working at 133, but at 165 - not at all!), now you understand why. But not everyone learned this lesson. There is no need to go far for examples: the VIA K8T800 chipset released at the beginning of the Athlon 64 era. Having quite good functionality and price, it simply cannot fix PCI \\ AGP \\ S-ATA frequencies when HTT is raised. That is, you will not get more than 220-230Mhz gain on the clock generator. That's so, sad gentlemen. Be careful not to fall for such a chipset (although it is already a little old).

Thus, we put an end to this section of the article and move on to the next. We considered the theoretical part a little, plus a few nuances that may get in your way. It's time, perhaps, to get down to business. At the same time, figuring out along the way what other sticks have to be removed from the wheels.

To be continued…

A motherboard is a printed circuit board (PCB) that connects the processor, memory, and all of your expansion cards together to keep your computer running smoothly. When choosing a motherboard, you need to consider its form factor. The form factor is a world standard that determines the size of the motherboard, the location of interfaces, ports, sockets, slots, the place of attachment to the case, the connector for connecting the power supply.

Form factor

Most motherboards currently made are ATX, such motherboards measure 30.5 x 24.4 cm. Slightly smaller (24.4 x 24.4 cm) mATX form factor. Mini-ITX motherboards are very modest in size (17 x 17 cm). ATX motherboard has standard connectors like PS / 2 ports, USB ports, parallel port, serial port, BIOS built into motherboard, etc. ATX motherboard is installed in a standard case.

Motherboard chipset

Typically, the motherboard has various slots and connectors. A chipset is all the microcircuits on the motherboard that ensure the interaction of all computer subsystems. The main chipset manufacturers at the moment are Intel, nVidia and ATI (AMD). The chipset includes north and south bridge.

Intel P67 chipset schematic

North bridge designed to support the video card and RAM and work directly with the processor. In addition, the northbridge controls the system bus frequency. However, today, the controller is often built into the processor, this significantly reduces heat generation and simplifies the operation of system controllers.

South bridge provides input and output functions, and contains controllers for peripheral devices such as audio, hDD and others. It also contains bus controllers to help you connect peripheralsfor example USB or PCI bus.

The speed of the computer depends on how coordinated the interaction of the chipset and the processor is. To be more efficient, the processor and chipset must be from the same manufacturer. In addition, it should be borne in mind that the chipset must match the size and type of RAM.

Processor socket

Soket is a kind of socket in the motherboard that will match the socket of your processor and is intended for connecting it. It is the socket connector that separates the motherboards.

• Sockets starting with AM, FM and S support AMD processors.
• Sockets starting with LGA have support for Intel processors.

What type of socket corresponds to your processor, you will learn from the instructions for the processor itself, but in general the choice of the motherboard occurs simultaneously with the choice of the processor, they seem to be selected for each other.

RAM slots

When choosing a motherboard, the type and frequency of RAM is of great importance. At the moment, DDR3 memory is used with a frequency of 1066, 1333, 1600, 1800 or 2000 MHz, before it was DDR2, DDR and SDRAM. One type of memory cannot be connected to the motherboard if its connectors are for another type of memory. Although at the moment there are models of motherboards with slots for both DDR2 and DDR3. Despite the fact that RAM is connected to a motherboard designed for a higher frequency, it is better not to do this, as this will negatively affect the operation of the computer. If in the future it is planned to increase the amount of RAM, then it is necessary to choose a motherboard with a large number of connectors for it (the maximum number is 4).

PCI slot

The PCI slot accepts expansion cards such as sound card, modem, TV tuners, lAN card, card wireless wi-Fi networks etc. We would like to note that the more these slots, the more additional devices you can connect to the motherboard. The presence of two or more identical PCI-E x16 slots for connecting video cards indicates the possibility of their simultaneous and parallel operation.

Due to the fact that modern additional devices include cooling systems and simply have an overall view, they can interfere with the connection of another device to an adjacent slot. Therefore, even if you are not going to connect a bunch of internal add-on cards to your computer, you should still choose a motherboard with at least 1-2 PCI slots so that you can easily connect even a minimal set of devices.

PCI Express

Slot PCI Express required to connect a PCI-E video card. Some boards with 2 or more pci-e connectors support SLI or Crossfire configuration for connecting multiple video cards at the same time. Therefore, if you need to connect two or three identical video cards at the same time, for example, for games or working with graphics, you must choose a motherboard with the appropriate number of slots. pCI type Express x16.

Bus frequency

Bus speed is the total bandwidth of the motherboard, and the higher it is, the faster the overall system performance will be. Please note that the processor bus frequency must match the motherboard bus frequency, otherwise a processor with a bus frequency higher than supported motherboardwill not work.

Hard drive connectors

The most relevant today is the SATA connector for connection hard driveswhich replaced the old IDE connector. Unlike IDE, SATA has a higher data transfer rate. Modern SATA 3 connectors support 6 Gb / s speeds. The more SATA connectors there are, the more hard drives you can connect to the motherboard. But keep in mind that the number of hard drives may be limited by the case of the system unit. Therefore, if you want to install more than two hard drives, then make sure that there is such an opportunity in the case.

Despite the fact that sATA connector is actively replacing IDE, new models of motherboards are still equipped with an IDE connector. To a greater extent, this is done for the convenience of the upgrade, that is, by updating the computer components in order to save all the available information on the old hard disk with an IDE connector and not have difficulties copying it.

If you buy a new computer and plan to use an old hard drive, then we recommend using it as an additional hard drive. It is better to rewrite the existing information to a new HDD with a SATA connection, since the old one will noticeably slow down the operation of the entire system.

USB connectors

Pay attention to the quantity USB connectors on the back of the motherboard. The more of them, the better, respectively, since almost all existing additional devices have exactly a USB connector for connecting to a computer, namely: keyboards, mice, flash drives, mobile phone, Wi-Fi adapter, printer, external hard drive, modem, etc. To use all these devices, you need a sufficient number of connectors for each device.

USB 3.0 is new standard transmission of information through USB interface, the data transfer rate reaches up to 4.8Gb / s.

Sound

Each motherboard has a sound controller. If you are a lover of listening to music, then we recommend choosing a motherboard with a large number of audio channels.

• 2.0 - the sound card supports stereo sound, two speakers or headphones;
• 5.1 - sound card supports audio system surround sound, namely 2 front speakers, 1 center channel, 2 rear speakers and a subwoofer;
• 7.1 - surround sound system support, has the same architecture as for 5.1 system, only side speakers are added.

If the motherboard has support for a multichannel audio system, then you can easily build a home theater based on a computer.

Additional functions

Fans can be connected to any motherboard that has connectors for fans (coolers) to ensure reliable and good cooling of all internal components in system unit... Several of these connectors are recommended.

Ethernet - This is a controller installed on the motherboard, with the help of which you connect to the Internet. If you plan to actively use the Internet, and your ISP supports a speed of 1 Gbps, then buy a motherboard that supports this speed. In general, if you buy a motherboard for a rather long period of time, and do not plan to change it in the next 3 years, then it is better to immediately take a card with support for a gigabit network, given the pace of technology development.

Wi-Fi built-in module, so you will need it if you have WI-FI router... By purchasing such a motherboard, you will get rid of unnecessary wires, but the truth is, Wi-Fi will not be able to please you with high speed, like Ethernet.

Bluetooth - a very useful thing, because thanks to the bluetooth controller, you can not only download content from a computer to your mobile phone, but also connect a wireless mouse and keyboard and even a Bluetooth headset, thereby getting rid of wires.

RAID controller- with it you can not be afraid for the safety of files on your computer in the event of a hard drive breakdown. To enable this technology, you must install. at least 2 identical hard drive in mirror mode, and all data from one drive will be automatically copied to another.

Solid Capacitors - this is the use of capacitors, which are more resistant to load and temperature, containing polymer. They have a longer lifespan and they tolerate heat better. Almost all manufacturers have already switched to them in the manufacture of motherboards.

Digital power system - provides power to the processor and the rest of the circuit without drops and in sufficient volume. On the market, there are both cheap digital blocks, which are no better than analog ones, and more expensive and skillful ones. It will be needed if you have a weak power supply or poor-quality electrical network, and you do not use a UPS, or you will overclock the processor.

Quick acceleration buttons - Allows you to increase the bus frequency or the applied voltage with one click. It will be useful for overclockers.

Static voltage protection - this problem seems insignificant until you reach for your pet in winter, having removed your sweater. And although this happens so infrequently, it is still very annoying to burn the board with one careless movement.

Military class- this is the passage of testing the board in conditions of high humidity, dryness, cold, heat, temperature drop and other stress tests. If the motherboard passes all these tests, it means that only a lightning strike can damage it. There are different classes that differ in the set of tests passed.

Multibiotic save you money and frustration after bad experiences with BIOS or UEFI. Otherwise, you will receive a non-working fee. And to restore it, you will need to find another working motherboard, preferably of the same type. On multi-BIOS boards, you can simply switch to UEFI backup. In some boards, this is implemented as a rollback to the original UEFI. Very useful for those who like to experiment.

Overclocked USB or LAN portsIs a technology found on almost all motherboards. Is that USB speed only increases under certain conditions. And you will notice an increase in the speed of the LAN network only when the ping in network games decreases

Mikhail Tychkov aka Hard

Good day.

If the processor is the heart personal computer, then the tires are arteries and veins through which
electrical signals. Strictly speaking, these are communication channels used to organize interaction between devices.
computer. By the way, if you think that those connectors where expansion cards are inserted are buses, then you are cruel
you are wrong. These are interfaces (slots, connectors), they are used to connect to buses, which, often, generally
not visible on motherboards.

There are three main indicators of tire performance. These are the clock frequency, bit width and baud rate.
data. Let's start in order.

Clock frequency

The operation of any digital computer depends on the clock frequency, which is determined by
quartz resonator. It is a tin container in which a quartz crystal is placed. Under influence
voltage fluctuations occur in the crystal. This very frequency of vibration and
called clock frequency... All changes in logic signals in any computer microcircuit occur through
certain intervals, which are called measures. Hence, we conclude that the smallest unit of time measurement for
most of the logical devices of a computer have a clock cycle or, in another way, a clock frequency period. Simply put - on
each operation requires at least one clock cycle (although some modern devices manage to perform several operations
per clock). Clock frequency, as applied to personal computers, is measured in MHz, where Hertz is one oscillation
per second, respectively 1 MHz - one million oscillations per second. In theory, if the system bus of your computer is
operates at a frequency of 100 MHz, which means it can perform up to 100,000,000 operations per second. By the way,
it is not at all necessary that each component of the system necessarily does something with each clock cycle. There are so
called empty clock cycles (wait cycles) when the device is in the process of waiting for a response from some other
devices. So, for example, the work of RAM and processor (CPU) is organized, the clock frequency of which is significantly
higher than the RAM clock speed.

Bit depth

The bus consists of several channels for transmitting electrical signals. If they say
that the bus is thirty-two-bit, this means that it is capable of transmitting electrical signals over thirty-two channels
at the same time. There is one thing here. The fact is that the bus of any declared bit width (8, 16, 32, 64) has, in fact
in fact, more channels. That is, if we take the same thirty-two-bit bus, then to transfer the actual data
32 channels are allocated, and additional channels are designed to convey specific information.

Baud rate

The name of this parameter speaks for itself. It is calculated using the formula:

clock frequency * bit width \u003d baud rate

Let's calculate the baud rate for a 64-bit system bus operating at a clock frequency
at 100 MHz.

100 * 64 \u003d 6400 Mbps

6400/8 \u003d 800 MB / s

But the resulting number is not real. In life, tires are influenced by a bunch of all sorts of factors:
inefficient conductivity of materials, interference, design and assembly flaws, and much more. For some
data, the difference between theoretical and practical data rates can be up to 25%.

Each bus is monitored by dedicated controllers. They are part of
recruitment system logic (chipset).

Now let's talk specifically about those buses that are present on the motherboard. Main
the system bus FSB (Front Side Bus) is considered. This bus transfers data between the processor and RAM,
and also between the processor and the rest of the personal computer devices. There is one pitfall here.
The fact is that while working on the material of this article, I ran into one confusion - there is such garbage as a tire
processor. According to some data, the system bus and the processor bus are one and the same, but according to others, they are not. I rummaged through a bunch of books
and reviewed a bunch of schemes. Conclusion: at first, the processor was connected to the main system bus through its own, processor,
bus, in modern systems these buses have become one whole. We say - the system bus, but we mean the processor bus, we
we say - processor bus, but we mean system bus. Let's move on. Phrase: “My motherboard is running at
100 MHz "means that the system bus operates at a clock frequency of 100 MHz. FSB bit width is equal to bit width
CPU. If you use 64 bit processor, and the system bus clock frequency is 100 MHz, the baud rate
will be equal to 800 MB / sec.

In addition to the system bus, there are also I / O buses on the motherboard that differ from each other.
on architecture. I will list some of them:

Processor bus - connects the processor to northbridge or a memory controller MCH. She works for frequencies 66-200 MHz and is used to transfer data between the processor and the main system bus or between the processor and external cache memory in systems based on 5th generation processors. Scheme of bus interaction in a typical computer based on pentium processor (Socket 7) is shown in the figure.

This figure clearly shows a three-tier architecture in which, in fact, upper level the hierarchy is, followed by the PCI bus and then the ISA bus. Most of the system components connect to one of these three buses.

In systems based on Socket 7 processors, an external L2 cache is installed on the motherboard and connected to the processor bus, which operates at a frequency motherboard (usually 66 to 100 MHz). Thus, with the appearance of Socket 7 processors with a higher clock frequency, the operating frequency of the cache memory remained equal to the relatively low frequency of the motherboard. For example, in the fastest Intel Socket 7 systems, the processor frequency is 233 MHz, and processor bus frequency with a multiplier of 3.5x it reaches only 66 MHz. Consequently, the L2 cache also operates at 66 MHz. Take, for example, a Socket 7 system using AMD K6-2 550 processors running at 550 MHz: with a 5.5x multiplier hprocessor bus frequency is equal to 100 MHz. Consequently, in these systems, the L2 cache only reaches 100 MHz.

The problem of slow L2 cache has been addressed in P6 class processors such as the Pentium Pro, Pentium II, Celeron, Pentium III, as well as AMD Athlon and Duron. These processors used Socket 8, Slot 1, Slot 2, Slot A, Socket A, or Socket 370. In addition, L2 cache was transferred from the motherboard directly to the processor and connected to it using an onboard bus. Now this bus has become known as the Front-Side Bus (FSB), however, according to the established tradition, I continue to call it the processor bus.

The inclusion of L2 cache in the processor has significantly improved its speed. In modern processors, the cache memory is located directly on the processor die, i.e. runs at processor frequency. In more early versions The L2 cache was located in a separate chip integrated into the processor case and operated at 1/2, 2/5, or 1/3 the processor frequency. However, even in this case, the speed of the integrated cache was significantly higher than the speed of the external cache, which was limited by the Socket 7 motherboard.

In Slot 1 systems, L2 cache was built into the processor, but only ran at half the frequency. Increasing the processor bus frequency from 66 to 100 MHz led to an increase in throughput up to 800 MB / s. It should be noted that most systems have included AGP support. The standard AGP is 66 MHz (double the PCI speed), but most systems support AGP 2x, which is twice as fast as AGP, resulting in an increase in bandwidth of up to 533 MB / s. In addition, these systems typically used PC100 SDRAM DIMMs with a transfer rate of 800 MB / s.

In Pentium III and Celeron systems, Slot 1 was replaced by Socket 370. This was mainly due to the fact that more modern processors include onboard L2 cache (operating at full core frequency), which means that the need for an expensive package containing several chips has disappeared. The processor bus speed increased to 133 MHz, which resulted in an increase in throughput to 1066 MB / s. In modern systems, AGP 4x is already used with a data transfer rate of 1066 MB / s.

Hub-based processor bus

Note the Intel hub architecture instead of the traditional north / south bridge architecture. In this design, the main connection between the components of the chipset is moved to a dedicated hub interface with a data transfer rate of 266 MB / s (double that of the PCI bus), which allowed PCI devices to use the full bandwidth of the PCI bus, excluding the south bridge. In addition, the Flash ROM BIOS, now called the Firmware Hub, connects to the system via the LPC bus. As noted, the North / South Bridge architecture used a Super I / O chip for this. Most systems now use the LPC bus to interconnect the Super I / O chip instead of the ISA bus. At the same time, the hub-architecture makes it possible to abandon the use of Super I / O. The ports supported by the Super I / O are called legacy, so the design without Super I / O is called legacy-free. In such a system, devices using standard portsmust be connected to the computer using the USB bus. These systems typically use two controllers and up to four shared ports (additional ports can be connected to USB nodes).

The systems based on AMD processors use the Socket A design, which uses faster processor and memory buses than Socket 370, but still retains the north / south bridge design. Pay attention to the high-speed processor bus, whose frequency reaches 333 MHz (bandwidth - 2664 MB / s), as well as the modules used dDR memory SDRAM DIMMs that support the same bandwidth (i.e. 2664 MB / s). It should also be noted that most of the south bridges include features common to Super I / O chips. These microcircuits are called Super South Bridge (super-south bridge).

The Pentium 4 system (Socket 423 or Socket 478) based on the hub architecture is shown in the figure below. A feature of this design is with a clock frequency of 400/533/800 MHz and a bandwidth of 3200/4266/6400 MB / s, respectively. It is the fastest bus today. Also take a look at the dual-channel PC3200 (DDR400) modules, whose bandwidth (3200 MB / s) matches the bandwidth of the processor bus, which allows you to maximize system performance. Higher performance systems that include a 6400 MB / s bus use dual channel DDR400 modules with a clock frequency of 400 MHz, bringing the total memory bus bandwidth up to 6400 MB / s. Processors with 533 MHz bus can use dual memory modules (PC2100 / DDR266 or PC2700 / DDR333) in dual channel mode to achieve 4266 MB / s memory bus bandwidth. Matching the memory bus bandwidth to the processor bus operating parameters is a prerequisite for optimal performance.