Today we look at the latency of RAM. What is it and why is this characteristic needed in computer technology? Where did she find her application? How to achieve the best value of this characteristic?
About RAM
This is the name of a special device in which data is stored and processes that are running while the computer is running are executed. Due to the speed of its action, it acts as an intermediary between the information located on the hard disk and the processor. The most understandable characteristic for most people is the amount of RAM. In this case, the rule works that the more it is, the better for us. In fact, now 2 GB are enough to use the Internet, watch movies and work with most useful programs. But to evaluate performance, a number of other parameters are also used, for example, frequency. It indicates how much data can be sent over the bus in one unit of time. The higher the frequency, the higher the speed of information transfer. But you need to consider that it is also supported by the processor and motherboard. Or let's take another parameter, not so famous - latency. So called time delays of signals that come from random access memory. The smaller the computer will work with, the better the result in terms of efficiency will ultimately turn out.
Latency features
In the previous paragraph, one significant point was missed. Along with the RAM frequency, the latency of the RAM is also growing. Which is better then OP? How to choose more or less universal indicators? It is considered optimal to use several memory models. So, if there are two of them, and they work in two-channel mode, then
the data transfer rate will be increased. For this, the used boards must be installed in specific slots (which, as a rule, are highlighted in one color). Here there is such a feature: it is not necessary that they have the same amount of memory. But regarding frequency it is desirable to get a complete match here. Otherwise, they will work with the smallest of these two.
What is memory latency?
A little more theory. This is the name of the summation, which is carried out using a special coefficient of uncontrolled reverse currents of transistors that are included in each chip of the used memory line, as well as the time of their switching. This may seem complicated, but it is a misleading assumption. So, latency depends on the frequency with which the chips work. Interestingly, it is not proportional. In other words: the lower the latency, the better for the user. Let's look at an example. We want our hypothetical
computer to have two gigabytes of
RAM . We can supply one line, which will give us 2 GB. But this is not the best way. In this case, it will be best to install four rulers, each of 512 MB. It should also take into account the influence of the motherboard, as well as the types of RAM used. A module made on the basis of one technology cannot be put in place that is intended for another technology. This is implemented in order to exclude damage during operation of a mechanism not intended for these conditions.
Designation
If you ever looked at devices, you might see something similar to the following: "RAM Latency: CL9." What does it mean? This indicator indicates a specific delay that occurs between the start of sending a column address to memory and, accordingly, the actual transfer of data. The number that is indicated indicates the amount needed to begin the process. The smaller it is, the better for us. Therefore, when choosing RAM, it is always necessary to take this value into account.
Device types
To separate by capabilities, a double data rate (DDR) is used, which can be translated as a double data rate. The very first samples of this technology had 184 contacts. Their standard supply voltage was 2.5 V. Sample 2 bits of data per clock cycle. But in our time they are considered obsolete and now they are practically nowhere and in no circumstances are used. More modern and the most common is DDR2. It allows you to immediately select 4 bits per cycle. The module is made in the form of a printed circuit board, which has 240 contacts (120 on each side). The standard power supply voltage for it is 1.8 V. A relatively new one is DDR3. He can sample in 8 bits of data in one cycle. It is also made on a printed circuit board, which has 230 pins. But the standard supply voltage in this case is only 1.5 V. There is also DDR4, but this is a new technology that is still very difficult to meet.
Throughput
Already we will complete the article about the latency of RAM. What was presented earlier is already enough to understand the bulk of information about the OP. And as a finishing touch - bandwidth. So, ideally, the value of this characteristic from the side of RAM should correspond to the size of the parameter of the processor. Consider this issue, considering that we have the previously mentioned two-channel mode. We have a processor with a bandwidth of 10,600 Mb / s. Then we can install the RAM module
, the characteristics of which will be 5300 Mb / s. Together they provide the same size of bandwidth. But do not forget that the modules must be of the same frequency. And it would be optimal if they also had the same volume, they were made by one manufacturer, and they were produced in the same batch. Then the latency of the RAM will tend to the lowest possible value. If we talk about the
dual-channel mode, then specifically for these cases they sell Kit. This is the name of special sets that are already optimized for such work. It should be noted that you can also use memory, whose throughput is higher than that of the processor. But this will not significantly affect latency, even if the difference is a multiple.
Conclusion
As you can see, RAM latency is a very important characteristic. Especially nice is that it can be influenced not only from the hardware side, but also by choosing the configuration for your computer. But at the same time, it is still necessary to stay within the reasonable framework and not to work in more than four-channel mode. No, of course, if you want, you can also build a computer with 512 MB
RAM cards that can boast a processing speed of 8 GB. But the effectiveness of this move will be rather doubtful. It is better to stop in this case on 4 boards, each of which will have 2 GB.