Computer terminology is sometimes striking in its complexity. Because of this, the user and at the same time the end customer are faced with certain selection problems when purchasing a computer or updating its configuration. One of the important characteristics of a PC is the so-called timing. RAM is characterized by both the frequency parameter at which it operates, and the size of the delay in accessing other computer modules.
Before proceeding to the answer to the question of what timing is, we will describe the basic principle of operation of RAM - random access memory.
How does RAM work?
Random access memory ( RAM) is one of the most important components of any computer. It temporarily stores data necessary for the processor to work. In this case, information is transferred directly from the memory block to the core or through a special ultrafast memory. In simple words, the RAM is a few microchips that store the data of all programs launched by the user. But isn’t it possible to store all this on the hard drive, because this is also memory? Unfortunately not. It's all about speed and reliability. A hard disk is a mechanical device with a low speed (compared to processor needs) and a limited resource. RAM is devoid of these shortcomings, it is fast, and its resource does not depend on the number of calls.
Classification
There are two kinds of memory:
- SRAM - static type of RAM;
- DRAM is a dynamic type of RAM.
Without going deeper into the technical implementation of SRAM memory, we can say that such strips are characterized by high speed. Delays and data transfer in the RAM block occurs instantly. But, unfortunately, such an implementation is expensive. In addition, the memory module is limited by the relatively large size of the transistors. SRAM modules are used as ultrafast cache memory, which is used on processors, hard drives and other PC modules.
The dynamic type of RAM is the rectangular bars that are familiar to everyone, which are located on the motherboard. Such a memory is characterized by comparative cheapness and large volumes. But its blocks have their drawbacks:
- Since the bar contains capacitors, it is necessary to regularly “regenerate” the charge in them so that the data does not disappear. This task is performed by the central processor. But during such access to the memory, all operations with it are suspended.
- The speed of such a bar is much less than that of a static one.
- Properly selected timing also plays a significant role. RAM with large volumes and high frequency will not always be able to show the necessary productivity due to high delays.
Types of RAM
At the moment, there are only 4 types of memory modules:
- DDR is an obsolete type of RAM that is used on very old computers.
- DDR2 - blocks of similar RAM can still be found in old PCs in government agencies and educational institutions. The speed of such a memory does not allow to cope with highly loaded modern applications, but it is sufficient for working with text editors and for surfing the Internet.
- DDR3 is the most common memory module. Energy consumption is 40% less than the previous type, and the speed of such a memory is much higher.
- DDR4 - the evolutionary development of RAM. Such modules are able to fully satisfy all the needs of the modern user. With an optimal configuration, the unit can provide a throughput of 34.1 GB / s.
Memory timings
Now we know what RAM is. Well, what is timing? This is the delay between sending and executing a memory bus command, which is measured in clock cycles.
DRAM consists of cells combined in two-dimensional arrays. The structure is similar to a lattice in which nodes there are cells. To access the nodes, the controller must know their address, consisting of the row number and column (coordinates). Individual arrays with the same cell size are combined into so-called banks.
Thus, the controller first accesses the bank with the line address through the RAS signal. Then the necessary line is searched - this is the RAS to CAS Delay timing cycle. After that, the controller sends the column number using the CAS signal. Waiting for a response to such a request is called CAS Latency. Timing under the name RAS Precharge indicates the time between closing and re-activating the line, Active to Precharge Delay - between activation and closing. Command Rate is the minimum interval between any two teams.
Buying a new RAM bar you can very easily determine the timing. RAM is marked with a standard circuit: DDR3 (frequency) CAS Latency - RAS to CAS DELAY - RAS Precharge - Cycle Time, which in reality looks like DDR3 2133 9-12-12-28.
Which is better - faster memory or less latency?
First of all, you need to pay attention to timing. RAM with a high frequency can run slowly, because access to the processor has a much lower speed, and therefore this advantage will not be realized. At the same time, delays always remain at the standard level, of course, if you do not set the memory timings manually.
So, for example, DDR2 1600 6-7-6-18 memory is much faster than DDR3 1866 9-9-9-24. As you can see, in the second case we have a more advanced generation of RAM with a higher frequency, but too much delays just level this fact. When acquiring new RAM, try to choose a model that has the minimum possible delay. This way you will ensure high performance of the computer as a whole.