Memory modules
The number of individual modules included in RAM kit. One module occupies one slot on the motherboard, so to install the entire kit, the number of free slots must be equal to or greater than the number of modules.
If there is an even number of modules in the set, they can be paired. This mode significantly increases the speed, but is not supported by all models of motherboards, so in each case this point should be clarified separately.
Now on the market? there are modules supplied in such quantity:
one modules,
set of 2 modules,
set of 4 modules,
set of 8 modules.
Form factor
A parameter that determines the physical dimensions of the memory module, as well as the number and arrangement of pins on it. To date, the most popular form factors are:
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DIMM. Classic full-size memory sticks, used mainly in desktop PCs. The number of contacts is usually between 168 and 240.
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SO-DIMM(Small Outline Dual In-Line Memory Module). A smaller version of the DIMM form factor designed for use in portable computing equipment such as laptops and tablet PCs. The number of contacts varies from 72 to 200.
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FB-DIMM(Fully Buffered Dual In-Line Memory Module). Memory modules with increased reliability due to the use of a buffer in the design (see Buffering support (Registered)). Most often used in servers. Similar in appearance to 240-pin DIMMs, but not compatible with them.
Memory rank
The number of ranks provided in the memory bar.
The rank in this case is called one logical module — a chipset with a total capacity of 64 bits. If there is more than one rank, this means that several logical ones are implemented on one physical module, and they use the data transmission channel alternately. A similar design is used in order to achieve large amounts of RAM with a limited number of slots for individual brackets. At the same time, it should be said that for consumer computers, you can not pay much attention to the memory rank — more precisely, peer-to-peer modules are quite enough for them. But for servers and powerful workstations, two-, four- and even eight-rank solutions are produced.
Note that other things being equal, a larger number of ranks allows achieving larger volumes, however, it requires more computing power and increases the load on the system.
Memory speed
The clock frequency of the RAM module.
The higher this indicator, the faster the “RAM” works, other things being equal, the higher its efficiency in games and other resource-intensive applications. On the other hand, a high clock frequency has a corresponding effect on the cost. In addition, in order to use the full capabilities of the memory, the motherboard to which the module is connected must support the appropriate frequency.
The most popular are modules with a frequency of
3200 and
3600 MHz - so to speak, universal workhorses. There are also more modest options - for example
2400,
2666,
2800,
2933,
3000 MHz. And advanced for serious tasks -
3866,
4000,
4800,
5200 MHz,
5600 MHz. High-frequency modules
6000 and
6400 MHz are also provided.
Clock speed
The amount of information that a memory module can receive or transmit in one second. The speed of the memory and, accordingly, the price of it directly depend on the bandwidth. At the same time, this is a rather specific parameter, which is relevant mainly for high-performance systems — gaming and workstations, servers, etc. If the RAM module is bought for a regular home or office system, you can not pay much attention to bandwidth.
Memory timing
Timing is a term that refers to the time it takes to complete an operation. To understand the timing scheme, you need to know that structurally RAM consists of banks (from 2 to 8 per module), each of which, in turn, has rows and columns, like a table; when accessing memory, the bank is selected first, then the row, then the column. The timing scheme shows the time during which the four main operations are performed when working with RAM, and is usually written in four digits in the format CL-Trcd-Trp-Tras, where
CL is the minimum delay between receiving a command to read data and the start of their transfer;
Trcd — the minimum time between the selection of a row and the selection of a column in it;
Trp is the minimum time to close a row, that is, the delay between the signal and the actual closing. Only one bank line can be opened at a time; Before opening the next line, you must close the previous one.
Tras — the minimum time the row is active, in other words, the shortest time after which the row can be commanded to close after it has been opened.
Time in the timing scheme is measured in cycles, so the actual memory performance depends not only on the timing scheme, but also on the clock frequency. For example, 1600 MHz 8-8-8-24 memory will run at the same speed as 800 MHz 4-4-4-12 memory—in either case timings, if expressed in nanoseconds, will be 5-5-5-15.
