How to calculate the bus bandwidth. The memory bandwidth of the video card and its dependence on the "bit rate

Now, having learned what it is and what and how it serves, many of you are probably thinking about purchasing a more powerful and productive RAM for your computer. After all, increasing the performance of a computer with the help of additional memory RAM is the simplest and cheapest (as opposed to, for example, a video card) method of upgrading your pet.

And ... Here you are standing at a display case with packages of RAMs. There are many of them and they are all different. Questions arise: Which one RAM select?How to choose the right RAM and not miscalculate?What if I buy a RAM, and then it will not work? These are reasonable questions. In this article I will try to answer all these questions. As you already understood, this article will take its rightful place in a series of articles in which I wrote about how to choose the right individual computer components, i.e. iron. If you haven't forgotten, it included articles:
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This cycle will be continued further, and at the end you will be able to assemble for yourself a super computer, perfect in every sense 🙂 (if, of course, finances allow :))
Until then learning to choose the right memory for your computer.
Go!

Random access memory and its main characteristics.

When choosing RAM for your computer, you must definitely build on your motherboard and processor, because RAM modules are installed on the motherboard and it also supports certain types of RAM. Thus, a relationship is obtained between motherboard, processor and RAM.

Learn about what kind of RAM does your motherboard and processor support? can be found on the manufacturer's website, where you need to find the model of your motherboard, and also find out what processors and RAM for them it supports. If you don't, it turns out that you bought a super modern RAM, but it is not compatible with your motherboard and will gather dust somewhere in your closet. Now let's go directly to the main technical characteristics of RAM, which will serve as a kind of criteria when choosing RAM. These include:

Here I have listed the main characteristics of RAM, which are worth paying attention to first of all when buying it. Now we will open each of them in turn.

RAM type.

Today the most preferred type of memory in the world is memory modules DDR(double data rate). They differ in release time and, of course, in technical parameters.

• DDR or DDR SDRAM(translated from English. Double Data Rate Synchronous Dynamic Random Access Memory - synchronous dynamic memory with random access and double data rate). Modules of this type have 184 contacts on the bar, are powered by a voltage of 2.5 V and have a clock frequency of up to 400 megahertz. This type of RAM is already outdated and is used only in old motherboards.
• DDR2 Is a widespread type of memory at this time. Has 240 pins on the printed circuit board (120 on each side). Consumption, unlike DDR1, is reduced to 1.8 V. The clock frequency ranges from 400 MHz to 800 MHz.
• DDR3- the leader in productivity at the time of this writing. It is not less widespread than DDR2 and consumes 30-40% less voltage than its predecessor (1.5 V). Has a clock frequency of up to 1800 MHz.
• DDR4- a new, super modern type of RAM, which is ahead of its counterparts both in performance (clock frequency) and voltage consumption (which means it has less heat). Support for frequencies from 2133 to 4266 MHz is announced. On the this moment these modules have not yet entered mass production (they promise to release them into mass production in mid-2012). Officially, modules fourth generation operating in the mode DDR4-2133 at a voltage of 1.2 V were presented at CES, by Samsung on January 04, 2011.

The amount of RAM.

I will not write much about the amount of memory. Let me just say that it is in this case that size matters 🙂
All a few years ago, 256-512 MB of RAM satisfied all the needs of even cool gaming computers. At the present time, for the normal functioning of a separate operating room windows systems 7 requires 1GB of storage, not to mention apps and games. There will never be extra RAM, but I'll tell you a secret that 32-bit windows uses only 3.25 GB of RAM, even if you install all 8 GB of RAM. You can read more about this.

The dimensions of the strips or the so-called Form factor.

Form - factor- these are the standard sizes of the RAM modules, the type of construction of the RAM strips themselves.
DIMM(Dual InLine Memory Module - double-sided type of modules with contacts on both sides) - mainly intended for desktop stationary computers, a SO-DIMM used in laptops.

Clock frequency.

This is pretty important technical parameter random access memory. But the motherboard also has a clock frequency and it is important to know the operating frequency of the bus of this board, since if you bought, for example, a RAM module DDR3-1800, and the slot (connector) of the motherboard supports the maximum clock frequency DDR3-1600, then the RAM module as a result will operate at a clock frequency of 1600 MHz... In this case, all sorts of failures, errors in the operation of the system, etc., are possible.

Note: Memory bus frequency and processor frequency are completely different concepts.

From the above tables, it can be understood that the bus frequency multiplied by 2 gives the effective memory frequency (indicated in the "chip" column), i.e. gives us the baud rate. The name also tells us about it. DDR(Double Data Rate) - which means double data transfer rate.
For clarity, I will give an example of decoding in the name of the RAM module - Kingston / PC2-9600 / DDR3 (DIMM) / 2Gb / 1200MHz, where:
- Kingston- manufacturer;
- PC2-9600- the name of the module and its bandwidth;
- DDR3 (DIMM)- type of memory (form factor in which the module is made);
- 2Gb- the volume of the module;
- 1200MHz- effective frequency, 1200 MHz.

Bandwidth.

Bandwidth Is a memory characteristic that affects system performance. It is expressed as the product of the system bus frequency by the amount of data transmitted per clock cycle. Bandwidth (Peak Data Rate) is a complex measure of capability RAM, it takes into account data transmission frequency, bus width and the number of memory channels. Frequency indicates the potential of the memory bus per clock cycle - higher frequencies can transfer more data.
The peak rate is calculated using the formula: B = f * c, where:
B - bandwidth, f - transmission frequency, c - bus width. If you use two channels for data transmission, we multiply everything received by 2. To get the number in bytes / s, you need to divide the result by 8 (since there are 8 bits in 1 byte).
For better performance RAM bus bandwidth and processor bus bandwidth must match. For example, for an Intel core 2 duo E6850 processor with a 1333 MHz system bus and a bandwidth of 10600 Mb / s, you can install two modules with a bandwidth of 5300 Mb / s each (PC2-5300), in total they will have the system bus bandwidth (FSB) equal to 10600 Mb / s.
Bus frequency and bandwidth indicate in the following way: « DDR2-XXXX" and " PC2-YYYY". Here "XXXX" stands for the effective memory frequency and "YYYY" for the peak bandwidth.

Timings (latency).

Timings (or latency)- these are the signal time delays, which, in the technical characteristics of the RAM, are written in the form " 2-2-2 " or " 3-3-3 " etc. Each digit here represents a parameter. In order, it is always “ CAS Latency"(Working cycle time)," RAS to CAS Delay" (time full access) and " RAS Precharge Time"(Pre-charge time).

Note

So that you can better understand the concept of timings, imagine a book, it will be our RAM, which we refer to. Information (data) in a book (RAM) is divided into chapters, and chapters consist of pages, which in turn contain tables with cells (as in Excel spreadsheets). Each cell with data on the page has its own coordinates vertically (columns) and horizontally (rows). The RAS (Raw Address Strobe) signal is used to select a row, and the CAS (Column Address Strobe) signal is used to read a word (data) from the selected row (i.e., to select a column). A full reading cycle begins with the opening of the "page" and ends with its closing and recharging, because otherwise the cells will be discharged and the data will disappear. This is how the algorithm for reading data from memory looks like:

1. the selected "page" is activated by the RAS signal;
2. data from the selected line on the page is transmitted to the amplifier, and a delay is required for data transmission (it is called RAS-to-CAS);
3. a CAS signal is given to select (column) a word from that row;
4. data is transferred to the bus (from where it goes to the memory controller), while there is also a delay (CAS Latency);
5. the next word goes without delay, since it is contained in the prepared line;
6. after the call to the row is completed, the page is closed, the data is returned to the cells and the page is recharged (the delay is called RAS Precharge).

Each digit in the designation indicates how many bus clock cycles the signal will be delayed. Timings are measured in nano seconds. The numbers can range from 2 to 9. But sometimes a fourth is added to these three parameters (for example: 2-3-3-8), called “ DRAM Cycle Time Tras / Trc”(Characterizes the speed of the entire memory chip as a whole).
It happens that sometimes a cunning manufacturer indicates only one value in the characteristics of the RAM, for example, “ CL2"(CAS Latency), the first timing is equal to two clock cycles. But the first parameter does not have to be equal to all timings, and maybe less than others, so keep this in mind and do not fall for the manufacturer's marketing ploy.
An example for clarity of the effect of timings on performance: a system with memory at a frequency of 100 MHz with timings 2-2-2 has approximately the same performance as the same system at a frequency of 112 MHz, but with delays of 3-3-3. In other words, depending on latency, the difference in performance can be up to 10%.
So, when choosing, it is better to buy memory with the lowest timings, and if you want to add a module to the already installed one, then the timings of the purchased memory must match the timings of the installed memory.

Memory operation modes.

The RAM can work in several modes, if, of course, such modes are supported by the motherboard. This single-channel, two-channel, three-channel and even four-channel modes. Therefore, when choosing RAM, you should pay attention to this parameter of modules.
Theoretically, the speed of the memory subsystem in the dual-channel mode increases 2 times, in the three-channel mode - 3 times, respectively, etc., but in practice, in the dual-channel mode, the performance gain, in contrast to the single-channel mode, is 10-70%.
Let's take a closer look at the types of modes:

• Single chanell mode(single-channel or asymmetric) - this mode is enabled when only one memory module is installed in the system or all modules differ from each other in terms of memory size, operating frequency or manufacturer. It doesn't matter in which slots and memory to install. All memory will run at the speed of the slowest memory installed.
• Dual Mode(two-channel or symmetric) - the same amount of RAM is installed in each channel (and theoretically, the maximum data transfer rate doubles). In dual-channel mode, memory modules work in pairs: 1st with 3rd and 2nd with 4th.
• Triple Mode(three-channel) - the same amount of RAM is installed in each of the three channels. Modules are selected in terms of speed and volume. To enable this mode, modules must be installed in slots 1, 3 and 5 / or 2, 4 and 6 slots. In practice, by the way, this mode is not always more productive than the two-channel mode, and sometimes even loses to it in the data transfer rate.
• Flex Mode(flexible) - allows you to increase the performance of RAM when installing two modules of different sizes, but the same operating frequency. As in the dual-channel mode, memory cards are installed in slots of the same name on different channels.

Usually the most common option is dual channel memory.
To work in multichannel modes, there are special sets of memory modules - the so-called Kit memory(Kit-set) - this set includes two (three) modules, of the same manufacturer, with the same frequency, timings and type of memory.
Appearance KIT-kits:
for two-channel mode

for three-channel mode

But the most important thing is that such modules are carefully selected and tested by the manufacturer itself, for operation in pairs (triplets) in two- (three-) channel modes and do not imply any surprises in operation and configuration.

Module manufacturer.

Now on the market RAM manufacturers such as: Hynix, amsung, Corsair, Kingmax, Transcend, Kingston, OCZ…
Each company has its own product for each product. marking number, according to which, if you decipher it correctly, you can learn a lot for yourself useful information about the product. For example, let's try to decipher the labeling of the module. Kingston families ValueRAM(see image):

Decoding:

• KVR- Kingston ValueRAM i.e. manufacturer
• 1066/1333 - working / effective frequency (Mhz)
• D3- memory type (DDR3)
• D (Dual) - rank / rank... A dual-rank module is two logical modules soldered on one physical channel and alternately using the same physical channel (needed to achieve the maximum amount of RAM with a limited number of slots)
• 4 - 4 DRAM memory chips
• R - Registered, indicates stable operation without failures or errors for as long as possible a continuous period of time
• 7 - signal delay (CAS = 7)
• S- thermal sensor on the module
• K2- a set (kit) of two modules
• 4G- the total volume of the whale (both planks) is 4 GB.

I will give another example of marking CM2X1024-6400C5:
The marking shows that it is DDR2 module volume 1024 MB standard PC2-6400 and delays CL = 5.
Stamps OCZ, Kingston and Corsair recommended for overclocking, i.e. have overclocking potential. They will be with small timings and a margin clock frequency, plus they are equipped with heatsinks, and some even coolers for heat dissipation. during acceleration, the amount of heat increases significantly. The price for them will naturally be much higher.
I advise you not to forget about fakes (there are a lot of them on the shelves) and buy RAM modules only in serious stores that will give you a guarantee.

Finally:
That's all. With the help of this article, I think you can no longer make a mistake when choosing RAM for your computer. Now you can choose the right RAM for the system and increase its performance without any problems. Well, for those who buy RAM (or have already bought it), I will devote the following article, in which I will describe in detail how to properly install RAM into the system. Do not miss…

Best RAM 2019

Corsair Dominator Platinum

The best memory among classmates with high performance and innovation in RGB technology. DDR4 standard, 3200MHz speed, default timings 16.18.18.36, two 16 GB modules. The strips feature bright Capellix RGB LEDs, an advanced iCUE program, and Dominator DHX heatsinks. The only problem is that the height of the module may not be suitable.

Corsair, as always, surpasses itself with each new model, the Dominator Platinum is no exception. Today it is the favorite DDR4 memory set for gamers and powerful workstation owners. The appearance of the modules is sleek and stylish, appealing to gaming enthusiasts, DHX cooling works efficiently, and the performance of the planks is already ready to become a legend. In any case, it will provide the user with flagship parameters for many years to come. Now in memory new design, new, brighter Corsair Capellix 12 LED illumination. The (proprietary) iCUE software provides flexible memory tuning for maximum performance. If you have changed the motherboard or processor, and maybe a graphics accelerator, memory can be configured as native for any new component.

The price tag of the memory is slightly higher than that of other manufacturers, but this is compensated highest quality and amazing performance.

In this article, we will consider 3 types of modern RAM for desktop computers:

• DDR- is the oldest type of RAM that you can still buy today, but its dawn has already passed, and this is the oldest type of RAM that we will consider. You will have to find far from new motherboards and processors that use this type of RAM, although many existing systems use DDR RAM. The operating voltage of DDR is 2.5 volts (it usually increases when the processor is overclocked), and it is the largest consumer of electricity out of the 3 types of memory we are considering.
• DDR2 is the most common type of memory used in modern computers... It is not the oldest, but also not the newest type of RAM. DDR2 is generally faster than DDR and therefore DDR2 has faster data transfer rates than the previous model (the slowest DDR2 model is equal in speed to the fastest DDR model). DDR2 consumes 1.8 volts and, like DDR, usually increases the voltage when the processor is overclocked
• DDR3- fast and new type of memory. Again, DDR3 is faster than DDR2, and thus the most low speed the same as the fastest DDR2 speed. DDR3 uses less power than other types of RAM. DDR3 draws 1.5 volts, and a little more when overclocking the processor

Table 1: Specifications of RAM according to JEDEC standards

JEDEC- Joint Electron Device Engineering Council

The most important characteristic on which memory performance depends is its bandwidth, which is expressed as the product of the system bus frequency by the amount of data transferred per clock cycle. Modern memory has a 64-bit wide bus (or 8 bytes), so the bandwidth of DDR400 memory is 400 MHz x 8 Bytes = 3200 MB per second (or 3.2 GB / s). Hence, another designation of this type of memory follows - PC3200. Recently, a dual-channel memory connection is often used, in which its bandwidth (theoretical) doubles. Thus, in the case of two DDR400 modules, we will get the maximum possible data exchange rate of 6.4 GB / s.

But the maximum memory performance is also affected by such important parameters as "memory timings".

It is known that the logical structure of a memory bank is two-dimensional array- the simplest matrix, each cell of which has its own address, row number and column number. To read the contents of an arbitrary cell in the array, the memory controller must set the RAS line number (Row Address Strobe) and the CAS column number (Column Address Strobe), from which the data is read. It is clear that there will always be some kind of delay (memory latency) between the submission of the command and its execution, and this is what these timings characterize. There are many different parameters that determine timings, but four of them are most commonly used:

• CAS Latency (CAS) - the delay in clock cycles between the CAS signal and the actual data output from the corresponding cell. One of the most important characteristics of any memory module;
• RAS to CAS Delay (tRCD) - the number of memory bus cycles that must pass after the RAS signal is sent before the CAS signal can be applied;
• Row Precharge (tRP) - time to close a memory page within one bank, spent on recharging it;
• Activate to Precharge (tRAS) - strobe active time. The minimum number of cycles between the activation command (RAS) and the precharge command, which ends with this line, or the closing of the same bank.

If you see the designations "2-2-2-5" or "3-4-4-7" on the modules, you can rest assured that these are the parameters mentioned above: CAS-tRCD-tRP-tRAS.

The standard CAS Latency values ​​for DDR memory are 2 and 2.5 clocks, where CAS Latency 2 means that data will be received only two clocks after receiving the Read command. In some systems, the values ​​are 3 or 1.5, and for DDR2-800, for example, latest version The JEDEC standard defines this parameter in the range from 4 to 6 clock cycles, while 4 is an extreme option for selected "overclocking" microcircuits. The latency of RAS-CAS and RAS Precharge is usually 2, 3, 4 or 5 clocks, and tRAS is a little more, from 5 to 15 clocks. Naturally, the lower these timings (at the same clock frequency), the higher the memory performance. For example, a module with a CAS latency of 2.5 usually performs better than a module with a latency of 3.0. Moreover, in a number of cases, memory with lower timings turns out to be faster, operating even at a lower clock frequency.

Tables 2-4 provide general DDR, DDR2, DDR3 memory speeds and specifications:

Table 2: Common DDR Memory Speeds and Specifications

Table 3: Common DDR2 Memory Speeds and Specifications

A type	Bus frequency	Baud rate	Timings	Notes
PC3-8500	533	1066	7-7-7-20	more commonly referred to as DDR3-1066
PC3-10666	667	1333	7-7-7-20	more commonly referred to as DDR3-1333
PC3-12800	800	1600	9-9-9-24	more commonly referred to as DDR3-1600
PC3-14400	900	1800	9-9-9-24	more commonly referred to as DDR3-1800
PC3-16000	1000	2000	TBD	more commonly referred to as DDR3-2000

Table 4: Common DDR3 Memory Speeds and Specifications

DDR3 can be called a newcomer among memory models. Memory modules of this kind are only available for about a year. The efficiency of this memory continues to grow, only recently hitting the JEDEC limits and beyond. Today DDR3-1600 (JEDEC's highest speed) is widely available and more manufacturers are already offering DDR3-1800). DDR3-2000 prototypes are shown on the market today and are expected to go on sale late this year or early next year.

The percentage of DDR3 memory modules entering the market, according to the manufacturers, is still small, in the range of 1% -2%, which means that DDR3 has a long way to go before it matches DDR sales (still within 12% - 16%) and this will allow DDR3 to come close to DDR2 sales. (25% -35% in terms of manufacturers).

Topic: PC Devices.

Study questions:

1. Devices that make up the PC architecture.

2. Internal devices PC.

3. External devices of the PC.

Modern computers are very diverse both in their structure and in the functions they perform.

If we consider computers by their functionality, we can conditionally classify them:

1. "Household" computers (PC);

2. "Educational" computers (simplified architecture);

3. "Professional" computers (workstations in production, in the office, etc.);

4. Computer servers (management of networked workstations, storage large arrays information, etc.), etc.

Depending on the functions performed and, thanks to the open architecture, the computer device is very diverse. As a result of scientific and technological development, the computer architecture is constantly being improved (evolved).

Open architecture of modern PCs:

Interface system

Computer architecture is the most general design principles that implement programmatic control of the interaction of its main units. Computer architecture is, first of all, blocks and devices, as well as the structure of connections between them.

The blocks and devices that make up the PC architecture are also divided into two groups:

· internal devices;

· external (peripheral) devices.

Internal devices probably received such a general name, since they are combined v one the case called system unit PC .

The appearance and dimensions of the cases of system units are varied. However, a mandatory element for all enclosures is connectors for connecting external devices and control interface.

With a huge variety of options made up of devices, systems placed in the case of the system unit, it is imperative minimum their picking.

"Required" include:

· Power Supply... On average, their power is 100 - 400 watts. The more devices in the system, the more great power must have a power supply. ( Average power 200 - 300 W).

· System (mother) board... This multifunction device is central to open architecture computers. Physically, it is a very complex multilayer printed circuit board.

In terms of functionality, the motherboard performs a set of functions for integrating devices and ensuring their interaction.

As the elements of the configuration of the architecture of the computer are standardized, the tendency is to include them in the composition of the motherboard.

The first motherboard was developed by IBM in August 1981 (PC-1). From the very beginning, the motherboard was conceived as a component that provides a mechanical connection and electrical connection between all other hardware. In addition to these functions, it also supplies electricity (power) to the computer components.

Architecture modern motherboard(generalized).

Modern MP contains a large number of controllers (specialized microprocessors) that ensure the interaction of all devices. They are implemented in two sets of microcircuits, historically called "northbridge" and "southbridge" or chipsets.

· Memory controller hub, or "north bridge"(English North Bridge) provides the processor, RAM and video subsystem;

· I / O controller hub, or "South Bridge"(eng. South Bridge) provides work with external devices.

Bus bandwidth.

The speed of the processor, RAM and peripheral devices differ significantly.

The performance of the device depends on:

· Clock frequency of data processing (usually measured in megahertz - MHz);

· And bit width, i.e. the number of data bits processed per clock cycle (the time interval between the supply of electrical pulses that synchronize the operation of PC devices).

Accordingly, the data transfer rate - the bandwidth of the buses connecting these devices should also differ. The bus bandwidth is equal to the bus width (bits) multiplied by the bus frequency (Hz - hertz. 1Hz = 1 cycle per second).

System bus(FSB stands for Front Side Bus) transfers data between the North Bridge and the microprocessor. In modern PCs, the system bus is 64-bit wide and has a frequency of 400 MHz to 1600 MHz.

The bandwidth can reach 12.5 GB / s.

Memory bus carries out data transfer between the "North Bridge" and PC RAM. Has the same performance as the system bus.

PCI Express bus(Peripherial Component Interconnect Bus Express - accelerated bus of interaction of peripheral devices) transfers data between the North Bridge and the video card (video card). The bandwidth of this bus can reach 32 GB / s.

SATA bus(English Serial Advanced Technology Attachment) transfers data between " South bridge"And the device external memory (hard drives, CD and DVD drives, floppy disks). The bandwidth can be up to 300 MB / s.

USB bus(English Universal Serial Bus) transfers data between the South Bridge and various external devices (scanners, digital cameras, etc.). Bandwidth up to 60 MB / s. Provides connection to a PC simultaneously up to 127 peripheral devices.

Other important functions of the motherboard- providing a mechanical connection and electrical connection between all other hardware, as well as supplying power to them.

There is a wide variety of design solutions for motherboards.

One of the characteristics of the motherboard is the form factor (AT / ATX). It determines the size of the motherboard and the locations of the hardware components on it.

Simplified layout of the joint venture components.

The central unit of the PC is considered to be an electronic unit located in a special connector on the motherboard, called CPU or microprocessor.

Initially, the microprocessor combined an arithmetic-logic device ( ALU) and control devices ( Uu).

The commands executed by the microprocessor usually involve arithmetic operations, logical operations, transfer of control and movement of data between registers, RAM and I / O ports. The microprocessor communicates with external devices thanks to its address, data and control buses, brought out to special contacts of the microcircuit case.

The control device generates control signals coming through the instruction buses to all computer blocks.

Simplified UU diagram

Command register- a storage register that stores the instruction code: the code of the operation to be performed and the addresses of the operands involved in the operation.

Firmware read-only memory- stores in its cells the control signals (impulses) necessary for the execution of information processing operations in the PC units. The operation decoder, reading the operation code from the command recorder, selects the required sequence of control signals in the firmware ROM - the command code.

Address generation node- a device that calculates the full address of a memory cell (register) according to the details coming from the command register.

Code buses of data, addresses and instructions- parts of the internal microprocessor bus that transfer signals between the processor and other PC devices.

In general UU generates control signals to perform the following basic procedures:

· Selections from the register - the counter of the RAM cell address, where the next program command is stored;

· Fetching from the RAM cells when the next command and receiving the read command into the command register;

· Decoding of the operation code and signs of the selected command;

· Reading from the corresponding to the decrypted code of operations of the ROM cells of the firmware of the control signals (pulses), which determine in all the computer blocks the procedure for performing the given operation, and sending the control signals to these blocks;

· Reading from the command register and the MPP register (microprocessor memory) of the individual constituent addresses of the operands;

· Selection of operands and execution of the specified operation of their processing;

· Recording results in memory;

· Formation of the address of the next program command.

Arithmetic logic unit designed to perform arithmetic and logical operations transformation of information.

1. Foreword

Recently, on "iron" sites in reviews, articles and forums, a lot has been said about the dependence of the speed of P4 on the bandwidth of the RAM. And Intel's policy, as can be seen from the news, is now aimed not so much at the processor component as at the development of dual-channel chipsets for its processors (Granite Bay, future Springdale and Canterwood). In the first synthetic tests that slipped through the network, they really show pretty good results. But what about real applications, in particular, in games? How important is memory bandwidth in Pentium 4 systems, and how much faster does dual channel memory provide?

2. Test configuration

A motherboard based on a dual-channel SiS-655 chipset (revision A0) - GigaByte GA-8SQ800, took part in my testing. As shown by the testing of boards based on this chipset, conducted at Anandtech.com and short review This particular board is already on our website, the SiS-655 is in no way inferior to the only dual-channel chipset available today from Intel - Granite Bay (i7205).

So the test configuration:

and the following memory modules:

• DDR 266MHz aka PC-2100 512Mb Samsung;
• DDR 333MHz aka PC-2700 512Mb Samsung;
• DDR 400MHz aka PC-3200 512Mb Samsung;
• 2хDDR 400MHz aka PC-3200 256Mb Samsung, the description can be found here.

For all of the above memory modules in Motherboard BIOS the boards were set at 2.5-4-4-7 timings - which allows us to speak about the correctness of the testing, by the way - for DDR 400 modules these timings were overclocked, since the standard timings for this memory are 3-4-4-7, but it It worked stably at low timings and the system did not crash or crash in any of the 6 tests. In dual-channel mode, the memory was identified by the motherboard as "Single 128 bit".

The tests were carried out at two different bus frequencies of the Pentium-4 processor: at a nominal frequency of 2.0GHz (100MHz x 4) and at overclocked to 3.0GHz (150MHz x 4). And, so to speak - "out of competition", I will give the test results on an even more overclocked system (up to 3.1GHz) and with memory overclocked to 412MHz. Why - you will understand below.

3. Testing technique

For testing, I used the following tests and games:

• 3DMark2001SE (Build 330)
• 3DMark2003
• Unreal Tournament 2003 (build 2107)
• Serious Sam: The Second Encounter v1.05
• Star Wars JK II: Jedi Outcast v1.02a
• Quake 3 Arena v1.27g

Testing was carried out in one resolution (1024x768x32bit) and in the following settings of the Catalyst 3.2 driver: everything in "Quality" mode, AF = 16 Quality, FSAA = Off, VSync = Off, Truform = Off (screenshot). I think that with weaker settings hardly anyone plays graphics in the Catalyst drivers on the Radeon-9700Pro, and enabling full-screen anti-aliasing (FSAA) or increasing the resolution would level the results by loading the video card "in full".

At the beginning of testing, I will give the results shown by Cachemem, MemTach, SiSoft Sandra 2003.3.9.44 and AIDA 3.33.6 in memory tests.

4. Test results

4.1. Synthetic memory bandwidth tests

To obtain more correct results, tests in each of the programs were performed 5 times. After each time the program was unloaded and loaded again. Average results are shown in tables and charts. By the way, there was practically no difference in the results obtained (3-15 units).

a) Cachemem

The lower (blue) results - the speed of reading the RAM, the upper (red) - records. As you can see, the main brake for Pentium 4 in both cases (100MHz and 150MHz) is DDR266 (PC-2100) memory. It is interesting to note that the 2 GHz pentium with dual-channel memory has almost come close to the 3 GHz pentium with PC-2700 memory, and even bypassed in speed. P4-3GHz + dual channel memory unrivaled.

b) MemTach

The results shown by Cachemem are repeated.

c) Sandra and AIDA

As you can see, the memory bandwidth is growing, and the two-channel is generally a champion. In all synthetic tests, P4-2GHz + DDR400 double is on par with P4-3GHz + 333. To begin with, very good and encouraging results.

Testing in both "brands" was carried out on default settings. I decided to combine the charts into one for b O of greater clarity. The bottom row of each table shows the percentage of performance gains when moving to faster memory. Ignore the difference in results between 2.0GHz and 3.0GHz, it should be;)

While the 3D Mark 2001 SE still somehow reacts to the RAM, the 2003 does not show itself at all. The only test that shows an increase is "Wings Of Fury". Although this is understandable - the video card is too weak for such a test.

Now about the memory. A slightly noticeable increase in speed is provided only by the transition from DDR266 to DDR333, and then the results are too close to each other to speak of the expediency of purchasing a second memory strip. There is no bottleneck for Pentium-4 when using DDR333 and higher in games. Moreover, both on the bus at 100 and 150MHz! And the 100MHz advantages of Pentium-4 3.1GHz with conventional memory easily outweigh the results with P4-3.0GHz with dual-channel memory.

Well, this is all synthetics, you say ("hey dear, what kind of omelet, but where are the eggs? !!");) Ok, let's go further ...

4.3. Unreal Tournament 2003

For testing, I used the utility [H] ardOCP UT2k3 Benchmark which allows you to choose the rendering method, resolution, and graphics quality settings in the game. After the tests are over, the program produces an html file with three tables with the minimum, average and peak FPS values ​​in each demo. Testing was carried out in all 7 available demos in High Quality mode, rendering method - Direct3D. The graph shows the average result.

Yes, and there is an increase here. But again, it is noticeable only when the memory is below 333MHz. And the above is again too weak for argumentation of a dual-channel chipset and memory. I don’t understand only in the "Asbestos" test why such a jump in performance occurred after overclocking the processor and memory to 3.1GHz and 412MHz, respectively (more than 45fps)? This is not a mistake or a typo, I tried it three times and all three times the fps value in this demo is over 200.

4.4. Serious Sam: The Second Encounter

Serious Sam - Second Coming was tested in the following settings: OpenGL, multitexturing, Quality, S3TC OFF, Truform = Off. Deeper graphics settings have not been changed (default).

This test is one of the few in this review that more or less noticeably responds to the speed of the memory subsystem. There is a slight increase everywhere, but it is especially noticeable when moving from DDR266 to DDR333. The difference between 3.0GHz + Double DDR and 3.1GHz + DDR 412MHz lies within the margin of error.

4.5. Quake 3 arena

Testing in Quake 3 Arena was carried out with maximum graphics settings in the game, without enabling texture compression. The Quake Arena version is 1.27g.

It can already be seen here that 2 gigahertz is quite enough for any memory except DDR266 (well, we have already heard that). But at 3GHz, the increase in speed is almost linear. The overclocked P4-3.1GHz + DDR412 is not far behind.

4.6. Star Wars JK II: Jedi Outcast

Here I also used the maximum graphics settings. The version of the game is 1.02a.

The situation is the same as with Quake 3.

At the beginning of the article, I did not want to make such a comparison, but after the tests carried out I decided to "spill balm" on my sick soul. Maybe dual-channel chipset / memory will show themselves here? For archiving, I chose a 560Mb file directory (117 folders, 726 files). Compressed with WinAce v2.5 archiver, with maximum compression ratio, dictionary of 4096Kb and adding information for recovery (Recovery record). Encoding to MP3 was performed with Easy Audio File Converter from Easy CD Extractor 5.07b2. Album: Madonna "Ray Of Light", 1998, 13 tracks, 674Mb, duration - 1:06:42. Compressed to Stereo, Highest Quality, VBR = 0 (highest), Filtering = Off. Tracks were previously grabbed onto a hard drive. Both archivers were run in the highest priority; during compression, no programs were launched, almost all residents were unloaded from memory, and no one even bothered the mouse.

Results:

I think no comments are needed here either.

5. Results and conclusions

Honestly, the test results just "killed" me. I waited b O only in old and not very demanding games, and when it comes to "serious" graphics, the power of the video card comes to the fore (well, this is quite natural). to say that with the Catalyst settings the effect of the graphics card performance prevails over the memory bandwidth and that the settings of the games themselves could have been made simpler, but is the Radeon-9700Pro bought in order to play at Low Quality? 200 (800) MHz bus, there will be more sense from dual-channel chipsets in games. The only thing that can be definitely stated is that DDR266 memory is strictly contraindicated for Pentium 4! But I dare to assume that among those who bought Pentium-4, there are hardly those who bought PC-2100 memory. In general, how many such useless computer "gadgets" do we already have?

• AGP8x is an extremely "useful" and necessary thing;)
• Serial ATA is the "future hard drives! ", but for some reason, when you mention it, they talk more about thin cables than about increasing the speed of hard drives;
• Hyper-Threading - 3-5% speed increase in optimized applications for this technology;
• now dual-channel chipsets have arrived ...

Of course, we can say that all this has been done for the future and after a while will be in demand, but no one talks about exactly when and where?

6. After completing the tests

After all the tests were completed, I came across an article on IXBT about testing motherboards based on SiS-655 and 658 chipsets, the results of which said about a slight speed advantage of the "Dual 64bit" memory mode over "Single 128bit". To check this, I turned on the "Dual 64 bit" mode in the motherboard BIOS and ran 3D Mark 2001 SE and WinAce archiving again. Indeed: the 3D Mark Score has grown by 100 parrots and the compression time has decreased by 1:28 minutes! At least a little better :)

This article was submitted to our second competition.