Smartphone memory bus bandwidth how to find out. RAM
We continue a series of articles on the analysis of the main characteristics of a video card, and next in line we have: memory bandwidth, as well as an indicator that directly affects it - the widthvideo memory bus.
Bus width or how many bits "need"
The memory bus width is the most important parameter that indirectly affects the overall performance of a video card. The bus itself is a channel that connects the memory and graphics processor of a video card. And the amount of data that can be transferred to the GPU and back to memory per unit of time depends on the width of the bus. Accordingly, the wider the video memory bus, the better. The increase in performance is especially noticeable in demanding games, which are reinforced by the heaviness in the form of maximum smoothing and anisotropic filtering.
Now, let's look at several popular memory bus "bitness" classes:
64-bit is a fairly popular class of video cards in the budget segment of the market. Video cards with such a bus are positioned for "ennoblement" budget systems(but even then, integrated solutions often reign there), as well as home PCs with undemanding tasks for the graphic performance of the system. Such video cards with large video memory on board.
128 bits is the middle class. Occasionally, it can be seen in budget video cards, and very often in middle-segment video cards. Often, such video cards are suitable for full-fledged home systems with fairly wide gaming tasks, but some games will still be “unbearable” for this class.
256 and 384 bits are the top class. Often, "goes" in combination with excellent frequency performance, both memory and core, of course - this is the maximum gaming performance for everything at once.
But, I would like to emphasize that this classification is very, very conditional, because you cannot evaluate a video card by the memory bus width alone. In addition, the “bitness” itself affects performance only with a strong dependence on the frequency of the video memory. These two parameters calculate the video card's memory bandwidth (PSB).
Therefore, in order to confidently speak about the optimal tire size, you need to consider everything as a whole, that is, the memory bandwidth itself. What are we going to do now.
Memory Bandwidth
As mentioned above, this indicator depends on two parameters: memory frequency and bus width.
Using a simple formula, you can find the memory bandwidth, for example, one of the video cards on the Radeon HD 7970 chip.
Let's take a model with an effective memory frequency of 6000 MHz and a bus width of 384 bits (48 bytes if translated). Memory bandwidth = effective memory frequency x memory bus width = 6000 x 48 = 288 GB/s. The memory bandwidth can also be viewed using special programs, for example, GPU-z.
Also, I suggest that you familiarize yourself with a rather interesting scale of the relevance of the memory bandwidth of modern video cards. Of course, everything here is also very ambiguous - after all, “we don’t live only in the PSP”, but still, a completely logical dependence can be traced:
What is the optimal tire width? Answer to this question for each case will be different. First, you need to build on the tasks that will be performed using the future system. Secondly, you need to remember about the balance in the parameters of the video card. Therefore, for a certain configuration, a video card with a certain bus width and other indicators must be selected. And they depend on the tasks and only on them.
PSP paired with a tire width will not make “weather” if the video camera is equipped with a weak GPU, with poor frequency performance. The GPU simply will not be able to “digest” the volumes of data that will come from a faster bus.
Therefore, as a result, we can boldly remind you again: balance and again balance!
Processor bus- connects the processor to the northbridge or 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 in systems based on fifth generation processors. The scheme of bus interaction in a typical computer based on the Pentium processor (Socket 7) is shown in the figure.
This figure clearly shows a three-tier architecture, in which at the top level of the hierarchy is located, followed by the PCI bus and then the ISA bus. Most system components are connected 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 runs at the motherboard's frequency (typically 66 to 100 MHz). Thus, when Socket 7 processors with a higher clock speed appeared, 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 at a multiplier of 3.5x it reaches only 66 MHz. Therefore, the L2 cache also runs at 66 MHz. Take, for example, a Socket 7 system using AMD K6-2 550 processors running at 550 MHz: at a multiplier of 5.5x hprocessor bus speed is equal to 100 MHz. Therefore, in these systems, the L2 cache frequency only reaches 100 MHz.
The slow L2 cache issue has been addressed in P6-class processors such as the Pentium Pro, Pentium II, Celeron, Pentium III, and AMD Athlon and Duron. These processors used Socket 8, Slot 1, Slot 2, Slot A, Socket A, or Socket 370. In addition, the L2 cache was moved from the motherboard directly to the processor and connected to it using an on-board bus. Now this bus has become known as the front-side bus (FSB), but I, according to established tradition, continue to call it the processor bus.
The inclusion of a second-level cache in the processor made it possible to significantly increase its speed. In modern processors, cache memory is located directly on the processor chip, i.e. runs at the processor speed. In earlier versions, the L2 cache was on a separate chip integrated into the processor package and ran at 1/2, 2/5, or 1/3 of the processor frequency. However, even in this case, the speed of the integrated cache memory was significantly higher than the speed of the external cache, limited by the frequency of the Socket 7 motherboard.
In Slot 1 systems, L2 cache was built into the processor, but only ran at half its frequency. Increasing the processor bus frequency from 66 to 100 MHz resulted in an increase in throughput to 800 MB/s. It should be noted that AGP support has been included in most systems. The standard AGP interface is clocked at 66MHz (twice the speed of PCI), but most systems support an AGP 2x port that is twice the speed of standard AGP, resulting in a throughput increase of up to 533MB/s. In addition, these systems typically used PC100 SDRAM DIMMs with a data transfer rate of 800 MB/s.
In Pentium III and Celeron systems, Slot 1 has been replaced by Socket 370. This was mainly due to the fact that more modern processors include on-chip L2 cache (running at full core frequency), which means that the need for expensive package containing several chips. The processor bus speed increased to 133 MHz, which resulted in an increase in throughput to 1066 MB / s. AT modern systems AGP 4x is already used with a data transfer rate of 1066 MB / s.
Processor bus based on hub architecture
Note the Intel hub architecture used instead of the traditional northbridge/southbridge 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 (twice that of the PCI bus), which allows PCI devices to use the full bandwidth of the PCI bus, without taking into account the southbridge. In addition, the Flash ROM BIOS chip, now called the Firmware Hub, is connected to the system via the LPC bus. As already noted, in the north/south bridge architecture, the Super I/O chip was used for this. Most systems now use the LPC bus instead of the ISA bus to connect the Super I/O chip. At the same time, the hub architecture allows you to abandon the use of Super I / O. The ports supported by the Super I/O chip are called legacy, so the non-Super I/O design is called a legacy-free system. In such a system, devices using standard ports must 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 hosts).
AMD-based systems use the Socket A design, which uses a faster processor and memory bus than Socket 370, but still retains the north/south bridge design. Note the processor's fast bus speed of up to 333 MHz (2664 MB/s bandwidth) and the DDR SDRAM DIMMs used that support the same bandwidth (ie 2664 MB/s). It should also be noted that most southbridges include features found on Super I/O chips. These microcircuits are called Super South Bridge (Super South Bridge).
A 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 throughput respectively 3200/4266/6400 MB/s. Today it is the fastest tire. Also look out for the dual-channel PC3200 (DDR400) modules, whose 3200 MB/s bandwidth matches the CPU bus bandwidth to maximize system performance. Higher performance systems that include a 6400 MB/s bus use dual-channel DDR400 modules at 400 MHz, bringing the total memory bus throughput to 6400 MB/s. 533MHz processors can use dual memory modules (PC2100/DDR266 or PC2700/DDR333) in dual-channel mode to achieve 4266MB/s memory bus bandwidth. Matching the bandwidth of the memory bus with the operating parameters of the processor bus is a condition for optimal performance.
Now, having learned what it is and why and how it serves, many of you are probably thinking about getting a more powerful and productive RAM for your computer. After all, increasing computer performance with the help of additional memory RAM is the simplest and cheapest (unlike a video card, for example) method of upgrading your pet.
And ... Here you are standing at the showcase with packages of RAM. There are many and they are all different. Questions arise: And what RAM to choose?How to choose the right RAM and not miscalculate?What if I buy a RAM, and then it will not work? These are perfectly 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 the series of articles in which I wrote about how to choose the right individual computer components i.e. iron. If you haven't forgotten, the articles included:
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This cycle will continue further, and at the end you will be able to assemble a perfect super computer for yourself in every sense 🙂 (if finances allow, of course :))
In the meantime learning how to choose the right RAM for your computer.
Go!
RAM 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, the relationship between the motherboard, processor and RAM is obtained.
Find out about What RAM does your motherboard and processor support? you can visit the manufacturer's website, where you need to find the model of your motherboard, as well as find out which processors and RAM it supports for them. If this is not done, it will turn 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 you should pay attention to first of all when buying it. Now let's open each of them in turn.
RAM type.
Today, the most preferred type of memory in the world are memory modules. DDR(double data rate). They differ in time of release and of course 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 the data transfer 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 obsolete and is used only in old motherboards.
- DDR2- a type of memory that is widely used at this time. It has 240 contacts 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 performance at the time of this writing. It is no less common than DDR2 and consumes 30-40% less voltage than its predecessor (1.5 V). Has a clock frequency up to 1800 MHz.
- DDR4- a new, super modern type of RAM, ahead of its counterparts both in performance (clock frequency) and voltage consumption (which means less heat dissipation). Announced support for frequencies from 2133 to 4266 MHz. At the moment, these modules have not yet entered mass production (they promise to release them into mass production in mid-2012). Officially, fourth-generation modules operating in the 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. Currently, for the normal functioning of the windows 7 operating system alone, 1 GB of memory is required, not to mention applications and games. There will never be an 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 slats or the so-called Form Factor.
Form-factor- these are the standard sizes of RAM modules, the type of design of the RAM strips themselves.
DIMM(Dual InLine Memory Module - double-sided type of modules with contacts on both sides) - mainly designed for desktop stationary computers, and SODIMM used in laptops.
Clock frequency.
This is a pretty important technical parameter of RAM. But the motherboard also has a clock frequency, and it is important to know the operating bus frequency 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 and are possible.
Note: Memory bus speed and processor speed are completely different concepts.
From the above tables, you can understand that the bus frequency, multiplied by 2, gives the effective memory frequency (indicated in the “chip” column), i.e. gives us the data transfer rate. The title tells us the same. DDR(Double Data Rate) - which means double the data 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 throughput;
- DDR3(DIMM)- type of memory (form factor in which the module is made);
— 2GB is the volume of the module;
- 1200MHz— effective frequency, 1200 MHz.
throughput.
Bandwidth- a characteristic of memory, on which the performance of the system depends. It is expressed as the product of the system bus frequency and the amount of data transmitted per clock cycle. Bandwidth (peak data rate) is a composite measure of the capability RAM, it takes into account baud rate, bus width and the number of memory channels. The frequency indicates the potential of the memory bus per clock - at a higher frequency, more data can be transferred.
The peak indicator is calculated by the formula: B=f*c, where:
B is the bandwidth, f is the transmission frequency, c is the bus width. If you use two channels for data transmission, we multiply everything received by 2. To get a figure in bytes / s, you need to divide the result by 8 (because there are 8 bits in 1 byte).
For better performance memory 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 a system bus bandwidth (FSB) equal to 10600 Mb/s.
Bus frequency and bandwidth are denoted as follows: " DDR2-XXXX" and " PC2-YYYY". Here "XXXX" indicates the effective memory frequency, and "YYYY" indicates the peak bandwidth.
Timings (latency).
Timings (or latency)- these are the time delays of the signal, which, in the technical characteristics of the RAM, are written as " 2-2-2 " or " 3-3-3 " etc. Each digit here expresses a parameter. In order, it's always CAS Latency” (cycle time), “ RAS to CAS Delay” (full access time) and “ RAS Precharge Time» (precharge time).
Note
So that you can better understand the concept of timings, imagine a book, it will be our RAM, which we access. Information (data) in a book (RAM) is divided into chapters, and chapters consist of pages, which in turn contain tables with cells (like in Excel tables). Each cell with data on the page has its own vertical (columns) and horizontal (rows) coordinates. 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 complete reading cycle begins with the opening of the "page" and ends with its closing and reloading, because. otherwise, the cells will be discharged and the data will be lost. This is how the algorithm for reading data from memory looks like:
- the selected "page" is activated by the RAS signal;
- data from the selected row on the page is transmitted to the amplifier, and the data transfer requires a delay (called RAS-to-CAS);
- a CAS signal is given to select (column) a word from that row;
- data is transferred to the bus (from where it goes to the memory controller), while there is also a delay (CAS Latency);
- next word goes already no delay, since it is contained in the prepared string;
- after the row access 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 cycles the signal will be delayed. Timings are measured in nano-seconds. The numbers can have values from 2 to 9 . But sometimes a fourth one is added to these three parameters (for example: 2-3-3-8 ), called " DRAM Cycle Time Tras/Trc” (characterizes the performance 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 cycles. But the first parameter does not have to be equal to all timings, and may be less than others, so keep this in mind and do not fall for the manufacturer's marketing ploy.
An example to illustrate the impact of timings on performance: a system with 100 MHz memory with 2-2-2 timings has approximately the same performance as the same system at 112 MHz, but with 3-3-3 delays. In other words, depending on latency, the performance difference can be as high as 10%.
So, when choosing, it is better to buy memory with the lowest timings, and if you want to add a module to an already installed one, then the timings of the purchased memory must match the timings of the installed memory.
Memory modes.
RAM can work in several modes, unless of course such modes are supported by the motherboard. it single channel, two-channel, three-channel and even four-channel modes. Therefore, when choosing RAM, you should pay attention to this parameter of the modules.
Theoretically, the speed of the memory subsystem in the dual-channel mode increases by 2 times, in the three-channel mode - by 3 times, respectively, etc., but in practice, in the dual-channel mode, the performance increase, in contrast to the single-channel mode, is 10-70%.
Let's take a closer look at the types of modes:
- Single channel 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, frequency of operation, or manufacturer. It does not matter in which slots and which memory to install. All memory will run at the speed of the slowest memory installed.
- dual mode(dual-channel or symmetrical) - the same amount of RAM is installed in each channel (and theoretically there is a doubling of the maximum data transfer rate). 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 by speed and volume. To enable this mode, modules must be installed in slots 1, 3, and 5/or 2, 4, and 6. In practice, by the way, this mode is not always more productive than dual-channel, and sometimes even loses to it in data transfer speed.
- Flex Mode(flexible) - allows you to increase the performance of RAM when installing two modules of different sizes, but the same frequency. As in the dual-channel mode, memory boards are installed in the same-named connectors of different channels.
Usually the most common option is dual-channel memory mode.
To work in multichannel modes, there are special sets of memory modules - the so-called Kit memory(Kit-set) - this kit includes two (three) modules, from the same manufacturer, with the same frequency, timings and memory type.
Appearance KITs:
for dual channel mode
for 3-channel mode
But the most important thing is that such modules are carefully selected and tested by the manufacturer to work in pairs (triples) in two- (three-) channel modes and do not imply any surprises in operation and configuration.
Module manufacturer.
Now on the market RAM well-established manufacturers such as: Hynix, amsung, Corsair, Kingmax, Transcend, Kingston, OCZ…
Each company has its own for each product. marking number, by 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 module marking Kingston families ValueRAM(see image):
Decryption:
- KVR– Kingston ValueRAM i.e. manufacturer
- 1066/1333 – operating/effective frequency (Mhz)
- D3- type of memory (DDR3)
- D (Dual) - rank / rank. A dual-rank module is two logical modules soldered on the same physical one and using the same physical channel in turn (required 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 and errors for as long as possible a continuous period of time
- 7 – signal delay (CAS=7 )
- S– temperature sensor on the module
- K2- a set (kit) of two modules
- 4G- the total volume of the whale (both bars) is 4 GB.
I will give another example of marking CM2X1024-6400C5:
It can be seen from the label that this 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 low timings and a clock frequency margin, plus they are equipped with heatsinks, and some even coolers to remove heat, because. 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 will not be mistaken when choosing RAM for your computer. Now you can choose the right operator for the system and improve its performance without any problems. Well, for those who buy RAM (or have already bought it), I will dedicate the next 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. Standard DDR4, speed 3200MHz, default timings 16.18.18.36, two modules of 16 gigabytes. The bars have bright Capellix RGB LEDs, an advanced iCUE program, and Dominator DHX heatsinks. The only problem is that the height of the module may not fit.
Corsair, as always, surpasses itself with each new model, Dominator Platinum is no exception. Today it is the favorite set of DDR4 memory for gamers and owners of powerful workstations. The appearance of the modules is sleek and stylish, appealing to gamers, DHX cooling works efficiently, and the performance of the bars is already ready to become a legend. In any case, for many years it will provide the user with flagship parameters. Now the memory new design, a new, brighter Corsair Capellix 12-LED backlight. Software (proprietary) iCUE provides flexible memory configuration for maximum performance. If you have changed the motherboard or processor, and maybe the graphics accelerator, you can configure the memory for any new component as native.
The price tag of the memory is slightly higher than that of other manufacturers, but this is compensated the highest quality and amazing performance.
In this article, we will look at 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 kind of RAM, although many existing systems use DDR RAM. The operating voltage of DDR is 2.5 volts (usually increases when the processor is overclocked), and is the largest consumer of electricity from the 3 types of memory we are considering.
- DDR2- This is the most common type of memory used in modern computers. It's not the oldest, but it's not newest look random access memory. DDR2 is generally faster than DDR, and therefore DDR2 has a higher data transfer rate 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, the voltage usually increases when the processor is overclocked.
- DDR3- fast and new memory type. Again, DDR3 is faster than DDR2, and thus the lowest speed is the same as the fastest DDR2 speed. DDR3 consumes less power than other types of RAM. DDR3 consumes 1.5 volts, and a little more when overclocking the processor
Table 1: Specifications RAM according to JEDEC standards
JEDEC- Joint Electron Device Engineering Council (Joint Engineering Council for Electronic Devices)
The most important characteristic on which memory performance depends is its bandwidth, which is expressed as the product of the system bus frequency and the amount of data transferred per cycle. Modern memory has a bus width of 64 bits (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 for this type of memory follows - PC3200. Recently, 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 a 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 array cell, the memory controller must specify the RAS row number (Row Adress Strobe) and the CAS column number (Column Adress Strobe), from which the data is read. It is clear that there will always be some kind of delay (memory latency) between the issuance of a command and its execution, and these very timings characterize it. There are many different parameters that determine timings, but four of them are most commonly used:
- CAS Latency (CAS) - the delay in cycles between the CAS signal and the actual output of data 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 given before the CAS signal can be sent;
- Row Precharge (tRP) - the time it takes to close a page of memory within one bank, spent on recharging it;
- Activate to Precharge (tRAS) - strobe active time. The minimum number of cycles between an activation command (RAS) and a precharge command (Precharge), which ends work on this line, or closes the same bank.
If you see the designations "2-2-2-5" or "3-4-4-7" on the modules, you can be sure that these are the parameters mentioned above: CAS-tRCD-tRP-tRAS.
The standard CAS Latency values for DDR memory are 2 and 2.5 cycles, where CAS Latency 2 means that data will be received only two cycles after the Read command is received. In some systems, values of 3 or 1.5 are possible, and for DDR2-800, for example, latest version The JEDEC standard defines this parameter in the range from 4 to 6 cycles, while 4 is an extreme option for selected "overclocker" microcircuits. RAS-CAS and RAS Precharge latency is typically 2, 3, 4, or 5 clocks, while tRAS is slightly longer, 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 one with a latency of 3.0. Moreover, in a number of cases, memory with lower timings, even at a lower clock frequency, turns out to be faster.
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
Type of | Bus frequency | Transfer 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, has only recently reached the JEDEC boundaries, and has gone beyond these boundaries. Today, DDR3-1600 (the highest speed of JEDEC) is widely available, and more manufacturers are already offering DDR3-1800). Prototypes of DDR3-2000 are shown on the modern market, and should go on sale at the end of this year - early next year.
The percentage of DDR3 memory modules entering the market, according to manufacturers, is still small, in the range of 1%-2%, which means that DDR3 has a long way to go before it can match DDR sales (still in the 12%-2% range). 16%) and this will allow DDR3 to get closer to DDR2 sales. (25%-35% according to manufacturers).
In the first PC - personal computers was measured in several kilobytes, then the bill went to megabytes, and now to gigabytes. At one time, 256 Mb DDR memory was quite enough for Windows XP, and most games did not require a large amount of DDR memory at all.
However, time does not stand still and the choice of RAM has expanded. Today, you can buy and install DDR3 or DDR4 RAM at any computer store. Modern Operating Systems and software require the use of high bandwidth memory.
Currently, in computer stores you can buy RAM of any type and any volume. There are practically no differences in memory cost between DDR3 and DDR4. Cost is determined only by bandwidth. Memory of the same size can cost several tens of dollars or several hundred, and does not mean at all that an expensive option will be better. Everything is determined by the requirements software and memory resources will not be used to the maximum.
RAM (RAM - random access memory) - part of the computer's memory system, which the processor can access in one operation.
While the computer is running, the data of the running program is stored in the RAM, which is processed by the central processor, otherwise it acts as an intermediary between the program and the processor. The volume of such data changes in real time and all information processed by the RAM disappears after the computer is turned off.
After years of computer operation, it may be necessary to replace the RAM to speed up the work.
In modern computers, made using technology DRAM(Dynamic random access memory - dynamic random access memory).
Our experts will help you make the right choice, select the required type of memory and install it on your desktop computer or laptop. In Kazan, the price is no more than 300 rubles.
When choosing RAM, consider the following characteristics:
- Memory type
- Memory Bandwidth
- Latency (timings)
- Memory size
RAM type
Depending on the form factor of the motherboard, the type of RAM used will depend. For example, it is not possible to install DDR3 RAM into the DDR2 memory socket. Form factors are designed to prevent erroneous connection of equipment. A module of one type of memory cannot be inserted into a slot designed for another type, thereby eliminating the possibility of damage to the module and the motherboard itself.
DDR
DDR(double data rate - double data transfer rate) - The memory module (PC-200, PC-400) has 184 contacts and a standard supply voltage of 2.5 V, at present this type of memory is outdated and practically not used.
DDR2
DDR2 The obsolete memory type used. DDR2 allows you to sample 4 bits of data per clock at once (4n-prefetch), and DDR only 2 bits per clock (2n-prefetch), i.e. is capable of transferring 4 bits of information from the cells of the memory chip to the I / O buffers on each cycle of the memory bus. The module is made in the form of a printed circuit board with 240 contacts (120 on each side) and has a standard supply voltage of 1.8 V.
DDR3
DDR3 - allows you to sample 8 bits of data per clock (8n-prefetch). The module, like DDR2, is made on a 240-pin board, and the standard supply voltage is only 1.5 V. The power consumption of DDR3 memory is approximately 40% less than that of DDR2 memory, which is very important for laptops and mobile systems.
Memory types
Module type | Rating | Bus frequency | Bandwidth (single-channel mode), Mb/s | Bandwidth (dual-channel mode), Mb/s |
PC2-5300 | DDR2-667 | 333 MHz | 5300 | 10600 |
PC2-6400 | DDR2-800 | 400 MHz | 6400 | 12800 |
PC2-8500 | DDR2-1066 | 533 MHz | 8500 | 17000 |
PC3-6400 | DDR3-800 | 400 MHz | 6400 | 12800 |
PC3-8500 | DDR3-1066 | 533 MHz | 8500 | 17000 |
PC3-10667 | DDR3-1333 | 667 MHz | 10600 | 21200 |
PC3-12800 | DDR3-1600 | 800 MHz | 12800 | 25600 |
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throughput
throughput directly affects the speed of the computer. For optimal interoperability, the bandwidth of the RAM bus must match the bandwidth of the processor bus.
For example, if the system has an Intel core 2 duo E6750 processor with a system bus (FSB) of 1333 MHz and a bandwidth of 10600 Mb / s, then you can install 2 PC2-5300 memory modules with a bandwidth of 5300 Mb / s each, which in a pair will be provide the same bandwidth (10600 Mb/s).
Installing two memory modules - allows you to use dual-channel mode. For dual-channel mode, memory modules must be of the same manufacturer, size, and frequency. It is best to use the so-called Kits. A kit is a kit, usually consisting of two memory modules that are already optimized for dual-channel operation. Of course, you can use memory with a higher bandwidth, such as PC2-6400, but significant increase you won't get performance. In addition, modules with a higher frequency have large timings (delays), which degrade performance. For example, performance in games will be higher if the timings are lower.
latency (timings)
latency (timings) - Signal time delays. Timing values usually look like 3-3-3-9 or 4-4-4-12, for example. In order, these are CAS Latency, RAS to CAS Delay, RAS Precharge Time, and DRAM Cycle Time Tras/Trc. Simply put, the lower the RAM timings, the better, provided that two identical modules work in dual-channel mode.
amount of RAM
amount of RAM- most commonly used modules are 512MB, 1024MB (1GB) and 2048MB (2GB). There is never a lot of RAM, the more there are, the better.
For a computer that is used to access the Internet and to work with office programs, 1GB of RAM is enough. To digitize video, work with graphics and for games, you need to have at least 2 or 4 GB.
The following brands can be distinguished from the most stable working memory modules:
Samsung, Corsair, OCZ, Transcend, Kingston, Patriot.
The specialists of our computer assistance will help identify the malfunction of the RAM, they can make a choice and install it at home in a matter of minutes.