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4 reasons why RAM timings matter
Typically speaking, the technical convention when it comes to computers is "more is better." More RAM, more storage, more Hertz, but there's more to computers than just more. In fact, one oft-overlooked feature of RAM is timings, which can be incredibly important and is separate to the speed of your RAM itself.
RAM timings are typically expressed as a string of four numbers, and you may have seen it written like 5-5-5-15 or 8-8-8-24. This is the time it takes your RAM to complete certain operations, and these numbers refer to the order of four separate parameters.
|
Name |
Symbol |
Definition |
|
CAS Latency |
CL |
The exact number of cycles between sending a column address to memory and the beginning of the data in response. |
|
Row Address to Column Address Delay |
T(RCD) |
The minimum number of clock cycles required between opening a row of memory and accessing columns within it. |
|
Row Pre-charge Time |
T(RP) |
The minimum number of clock cycles required between issuing the pre-charge command and opening the next row. |
|
Row Active Time |
T(RAS) |
The minimum number of clock cycles required between a row active command and issuing the pre-charge command. |
As a general rule, all timings work together and lower is better, but that isn't always the case. RAM speeds and timings work in tandem and you can get different results depending on how you match up your timings and your speeds. Timings basically affect how fast the computer can access the RAM, but the speed of RAM itself is the actual data transfer rate. As an example, a 2400 MHz CL15 DDR3 RAM stick will be faster than a 2400MHz CL16 DDR RAM stick.
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Pushing your RAM too far can cause system instability
Low latency is a bigger strain on RAM
Setting tighter timings on your RAM can be great for performance, but they also stress your RAM and your memory controller. You can get better performance, but your system could fail to boot or crash frequently, not unlike if you were to overclock your CPU too far.
However, don't just place the blame on your RAM if you can't tighten the timings the way you want to. Your motherboard could also be struggling to meet the demand being placed on it.
It can help or hinder your gaming performance
Tighter timings can improve gaming performance
When you're playing games on your PC, your CPU has to fetch instructions, decode them, and execute them. When instructions aren't in the CPU's cache, or a cache miss occurs, then the instructions are taken from memory. While you won't notice a huge difference in day-to-day tasks when it comes to memory timings and speed, gaming is an inherently latency-sensitive process on a computer. Any delay will have a direct effect on your framerate or frame times, and lower CAS latency can mean your memory responds to requests more frequently.
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Of course, there's more to this than just timings, and as already mentioned, RAM speed matters too. That's why memory overclockers try to strike a balance between timings and data transfer rates. You'll especially notice this in games where the CPU impacts the performance more than the GPU.
It can improve multitasking performance
Anything that heavily reads or writes memory will be influenced by timing
While your memory speed determines how much data can be transferred per second, timings affect how efficiently it's accessed and processed. Heavy applications like 3D rendering, video editing, or even just multitasking will frequently access memory, and your timings are important for that reason.
In other words, if you have lower latency and applications are constantly trying to access the memory in your computer, then you'll have better performance overall from those applications as they frequently access the RAM.
Sometimes, lower timings are better than data transfer rate
It depends on the application
Let's say you have two sticks of RAM, one CL14 3200 MHz stick, and one CL18 3600MHz stick. The 3200 MHz stick actually has a lower latency than the 3600 MHz stick, with the 3200 MHz RAM having a real-world latency of 8.75ns and the 3600 MHz RAM having a real-world latency of 10ns. This is calculated through the following formula:
Latency in nanoseconds = ((CAS latency) * 2000)/(RAM frequency) Latency is only a small part of the equation of course, but the point is that if you're worried about latency, you'll need to do some calculations first to make sure you're getting the lowest.
