What You Need to Know about RAM Speeds – Is Faster RAM Worth It?

ram speed

When buying RAM you’ll see these large numbers followed by MHz (Megahertz). You probably already know this represents the speed, at least in part, but what does RAM speed actually even do for your computer?

Is it good for gaming? Is higher MHz RAM better? And what’s the best RAM speed?

Faster RAM speeds allow your processor to access the data stored on it quicker, giving your system a boost in processor performance.

What is RAM?

Random Access Memory (RAM) is used as temporary, super fast data storage for your processor (CPU). When you launch a program, the hard drive sends the relative data for that program to the RAM, where the processor can access it much quicker than on the hard drive.

How does RAM work?

Random Access Memory is an integrated circuit chip made up of millions of transistors and capacitors. Each pair of transistor and capacitor make up a cell, and these cells are where the data is stored.

These cells hold and release electrical charges to write, rewrite, and erase data allowing data to constantly change much faster than your traditional mechanical drive (HDD) that uses platters and actuator arms, or even SSDs.

RAM is also volatile meaning that any data that is held within its cells will be lost when it loses power. This is why we don’t permanently write data to our RAM modules.

The Random Access part of Random Access Memory comes from the fact that data can be written to any cell in any order, and can be read from any cell as long as the physical location of the cell containing the data is known.

What does RAM Speed Do?

RAM speed is actually multifaceted. You can’t merely take the MHz as a measurement of speed and use that as the way you determine its speed. To find RAM speed you need to know the clock cycle and its latency.

Clock Cycles (RAM MHz)

RAM frequency works off of clock cycles (note: people often call this the RAM speed even though it is really only part of the speed equation). Each read and write is done on a cycle. RAM is measured by how many cycles per second it can perform. For example, if RAM is rated at 3200 MHz, it performs 3200 cycles per second.

The more of these cycles that happen per second, the more data can be stored and read, making for a smoother user experience.

CAS Latency

Column Access Strobe (CAS) latency, or CL, is the delay time of your RAM receiving a command and then being able to issue it. The numbers for the timings will look something like this 15-17-17-35. Those numbers indicate how many clock cycles it takes for the RAM to respond to the command.

Because the timings determine how fast your RAM will respond to a command. As such, faster MHz RAM with slower CAS timings might not be better than slower MHz RAM with faster CAS timings.

Finding Your REAL RAM Speed

In order to find the real speed of your RAM, you want to take the frequency of your RAM (let’s say it’s 3200 MHz), and divide it by the first number listed for the CAS timings, let’s say 14.

So that gives us 3200/14 = 228.58. This gives us how many instructions per second the RAM can carry out.

Now, let’s compare it to slower MHz RAM with a lower CAS timing.

We’ll use 2133 MHz RAM using a CAS latency of 6.

2133/6=355.5. This means that 2133 MHz RAM with a CAS latency of 6 will actually respond 55% faster!

Overclocking

By default, DDR4 RAM stock maximum clock speed is 2133 MHz. When you see RAM with speeds rated over this, it means the module is rated to be overclocked to that speed.

You may see mention of something about being AMD or Intel compatible, and this usually refers to the XMP profiles built in. This indicates it has profiles built into the module that allows your motherboard BIOS to automatically overclock your RAM to manufacturer-specified settings.

Even if it specifies either AMD or Intel, XMP profiles will usually work with either one, but you’ll need to check with your motherboard specs.

If you’re curious about how to make sure all of your hardware is compatible with each other, you should check out this article.

Can I mix RAM speeds?

This question is a little bit of a mixed bag. The short answer is yes, sometimes.

RAM itself is compatible with other RAM of different timings and speeds, but the further apart they are from each other in those attributes, the harder time your motherboard is going to have trying to run them together.

For example, two modules of RAM with the same speed (let’s say 2133 MHz) and slightly different CAS timings probably wouldn’t be an issue. Your motherboard would just pick the slowest one and run them both at those speeds.

The further away you get in speeds and timings, the harder time your motherboard is going to have trying to run them together, and it may require manual control over the speeds and timings in the form of over and underclocking the modules.

In other words, you could probably do it, but it would also definitely be a bigger headache than it is worth.

Bandwidth & Capacity

RAM speed doesn’t exist in isolation, you also must consider bandwidth and capacity when making a purchasing decision. Because of the quantity of factors, RAM bandwidth (and efficacy as a whole) can be a somewhat intricate topic that’s deserving of its own article (something we might just do in the near future).  

As a concept, it’s relatively simple: bandwidth affects how much data can get through at any given time. And of course, memory is the space.

Some like to explain RAM as being like a highway. The number of lanes, which allows more cars to go through, represents the bandwidth. The speed limit represents the literal speed. And memory is like a big parking garage that everyone is going into and out of (to help you play video games).

Notice, if you don’t have enough parking or lanes, or the speed limit is too low, then everything gets bogged down. (And if you bring civil engineering into my metaphor, then it falls apart completely.)

How much does RAM Speed Matter?

Alright, so we’ve figured out what RAM speeds are and how they work, and even how they affect your system. But how does it impact gaming? Is it worth it to buy RAM that’s rated a little higher to try and get those high FPS counts?

I’ve been curious about this myself many times and decided to do some testing of my own.

Here’s the system I’ll be using for the tests:

  • MSI Pro Carbon Gaming X370 Motherboard
  • AMD Ryzen 7 1700 @ 3.7 GHz
  • Gigabyte Aorus RX 580 XTR
  • 32GB G.Skill Flare X (CAS: 15) (technically two separate sticks of 16GB dual channel RAM)
  • 8GB G.Skill Ripjaw (CAS: 9)
  • Samsung Evo 960 M.2 SSD

Using this setup, I’ll be running six separate tests:

  1. Both G. Skill Flare X’s in dual channel at 32GB at both 2933 MHz and 2400 MHz
  2. A single G. Skill Flare X 16GB stick using speeds of 2933 MHz and 2400 MHz.
  3. The G.Skill Ripjaw 8GB stick will also be tested at speeds of 3600 Mhz and 2133 MHz.

Testing a range of RAM capacities and speeds will help give us a larger pool of information for both high end and budget builds alike.

For benchmarking, I’ll be using the Time Spy demo from 3DMark to test both CPU and GPU and track FPS. I’ll be running the same test for each RAM configuration.

32GB of RAM running at 2933 MHz

When testing our first RAM configuration, we saw a graphics score of 4475, with the first and second FPS tests (Graphics test 1 and 2) averaging 30/24 FPS respectively.

This gives us a test of how the hardware will do for gaming. The higher the score the better.

32GB of RAM running at 2933 MHz

When looking at the CPU score, which will be what you’re looking for in terms of CPU loading times, coming in at 7058 and scoring an average of 23 FPS during the test.

The overall Time Spy score was 4734.

32GB of RAM running at 2933 MHz
Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU TestTime Spy Score
(FPS)
447530.224.83705823.714734

32GB of RAM running at 2400 MHz

32GB of RAM running at 2400 MHz

When running our RAM in our second configuration, our results were pretty similar to the previous tests, really only seeing a difference in the CPU test.

32GB of RAM running at 2400 MHz
Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU Test (FPS)Time Spy Score
445830.0424.84693823.314710

As you can see, speed didn’t really make much of a difference here.

16GB of RAM running at 2933 MHz

16GB of RAM running at 2933 MHz

Dropping down from 32GB to half of that didn’t make much of a dent in the GPU tests, we really only see a difference when it comes to CPU testing.

16GB of RAM running at 2933 MHz
Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU Test (FPS)Time Spy Score
447530.2524.88634521.324681

16GB of RAM at 2400 MHz

16GB of RAM at 2400 MHz

Again, not a lot of difference in graphics tests, just CPU. And only barely even that.

16GB of RAM at 2400 MHz
Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU Test (FPS)Time Spy Score
445930.224.74605623.354642

8GB of RAM at 3600 MHz

8GB of RAM at 3600 MHz

Not a lot changed in the graphics department going down to even 8GB of RAM. Overall CPU score was a little higher than the 16GB of RAM clocked at a lower speed, but average FPS in the test went down.

8GB of RAM at 3600 MHz
Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU Test (FPS)Time Spy Score
446530.2524.77611420.544653

8GB of RAM at 2133 MHz

8GB of RAM at 2133 MHz

And here we have our final test. A mere 8GB clocked at stock 2133 MHz speeds, how will it fare?

8GB of RAM at 2133 MHz
Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU Test (FPS)Time Spy Score
447030.2224.85567819.084617

What Speed RAM Should I Get?

Speed RAM
 Graphics ScoreGraphics Test 1 (FPS)Graphics Test 2 (FPS)CPU ScoreCPU Test (FPS)Time Spy Score
32GB at 2933 MHz447530.224.83705823.714734
(most powerful)
8GB at 2133 MHz447030.2224.85567819.084617
(least powerful)
Difference5-0.02-0.0213804.63117

Even with as little as 8GB of RAM running at stock clock speeds, there’s no difference in performance in the benchmarks, at least as far as graphics are concerned. In fact, despite the RAM speed difference, there is no significant impact on graphics, just CPU tests.

This is because programs like games (with a few exceptions here and there) are more graphics intensive than anything else, and will require more work from your video card (and its built-in RAM) and processor than your RAM.

Where you will see major RAM speeds actually benefit you is when you’re doing multitasking like running multiple programs, or streaming while you game and even content creation.

Check out our buying guides on Best DDR3 & DDR4 Ram

Conclusion

So we’ve learned how RAM works, what the speeds tell us, and we’ve even looked at some benchmarks to find out exactly how it affects your system when it comes to graphics tasks vs processor tasks.

I currently run 32GB of RAM at 2933 MHz. I use my machine for high-end gaming, but also for content creation. What RAM speed and timing will you run?

Lets us know if this article helped in any way, or if you have other questions about RAM you’d like us to cover.

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