What You Need to Know about RAM Speed

After CPU and graphics card, RAM memory is the most decisive component of a PC.

Being a faster storage device, it acts as a bridge between your hard drive/SSD and the CPU cache.

When a computer program is executed, its data is sent over to the RAM. Due to the higher retrieval speed, CPU can access data from RAM much quickly which results in faster execution of that program.

When buying new RAM memory for their computers (or upgrading existing ones), most people only look at the size and not the speed of those memory modules. Surely, RAM size is important in determining whether you can run a particular game/software but RAM speed is equally crucial in this regard.

RAM Latency

RAM memory comes with a clock speed which determines how many read/write operations (also called cycles) it can be perform in one second. For example, a 3200MHz RAM can execute 3 billions instructions in one second. RAMs can be found with 2133MHz-4800MHz speed these days.

Up next is the Column Access Strobe/Signal (CAS) latency. Also known as CL, it refers to the number of cycles required by a RAM to respond to a request for data.

To calculate the actual latency of a RAM module, we’ll have to use both clock speed as well as CL latency, and use the following formula:

Latency (in nano seconds) = (CAS Latency/RAM Speed) x 2000

For example, a 3000 MHz RAM with 16 CAS latency will have a latency of 10.66 nanoseconds. CAS latency is important factor to consider when choosing a RAM because a seemingly faster RAM can actually be slower due to its high CL.

To find your CAS Latency, you’ll needed to find RAM timings. These are listed on the module package and is formatted as a sequence of four two-digit numbers separated by hyphens, such as 15-16-16-35. The first one of those number is the CAS Latency.

CPU and Motherboard Compatibility

We’re seeing high-speed RAM modules in the market lately, with some of them going as high as 4666-48000 MHz. But upon using them, you’ll find that the mentioned speed is its overclocked speed, and the speed you get out of the box is quite lesser.

To overclock the RAM to your desired clock speed, you’ll need to enable XMP of your RAM through the motherboard’s BIOS. While you can set your RAM clock speed to as high as 4800 MHz, your CPU and motherboard should be compatible with such speed.

Not every motherboard is suitable for overclocked RAM. That’s why you need to check reviews of your motherboard to know its overclockability. The same goes for your processor.

AMD processors are generally known to work better with RAM modules up to 4000 MHz which makes them suitable for high-speed modules. In intel processors, results are not as great.

With that said, you shouldn’t set your RAM clock speed too high as it can make the memory module unstable.

Also, the gain is not as high as you get in overlocking other components, such as CPU and graphics card.

Does RAM Speed Affect Performance?

Yes, RAM speed does affect performance, but it depends on what software/game you run.

In CPU-centric games like CS:GO, there’s a clear performance boost but in GPU-bound titles like GTA V and Assassins’s Creed: Valhalla, the performance gain is negligible.

It also depends on resolution at which you play games.

For example, you can get 15-20% more FPS in Far Cry 5 and Shadow of the Tomb Raider at 1080p resolution through XMP-profile RAM. But when you turn up the resolution to 1440p/4K, the difference gets negligible as the games turn to be more GPU-bound than CPU-bound – meaning it’s your GPU that will define the performance at that resolution.

Heck, even some CPU-centric titles such as Wildlands show only minor gain.

The best thing here is to research about each game you play and find out if it benefits from a higher-speed RAM.

Conclusion

If you already have a high-speed RAM then you should enable XMP to get the most performance juice out of it.

But if you’re in the market looking for a new RAM module, I would suggest you to go with a medium-speed RAM with more memory rather than high-speed RAM with small/medium size.

While you can tinker with the timings and clock speed of your RAM memory, it’s not worth the effort.

Higher speed RAMs come at a premium size, which you can saved by getting a slightly slower but cheaper model, and investing that money into another PC hardware component.

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Author
Dennis is the founder and chief editor of PCBuilderz.com. For almost 25 years, he’s been building PCs for himself, clients, and his friends. He has seen everything from those Core 2 processors to the latest Ryzen 5000 models. He aims to help people make the right decisions for their PC component build and upgrades.
Photo of author
Author
Dennis is the founder and chief editor of PCBuilderz.com. For almost 25 years, he’s been building PCs for himself, clients, and his friends. He has seen everything from those Core 2 processors to the latest Ryzen 5000 models. He aims to help people make the right decisions for their PC component build and upgrades.