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

RAM speed

For years now, PC enthusiasts have been obsessed with getting the fastest hardware components available for their new shiny builds. When it comes to RAM, though, this might not be the best way to go...

When buying RAM, you’ll see a large number followed by MHz (Megahertz). This, as you probably already know, represents the speed of the memory you're looking to purchase. But how does RAM speed affect your computer?

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

These are the sort of questions that gamers and keen PC builders ask themselves regularly and the very reason why we're going to try to explain EXACTLY what RAM speed does and whether it's worth the extra money.

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

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What Is RAM?

Random Access Memory (RAM) is used as a temporary, super-fast data storage for your processor (CPU). When you launch a program, the hard drive sends the relevant data for that program to the RAM, where the processor can access it much quicker than going directly to 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. This allows data to regularly change much faster than your traditional mechanical drive (HDD) that uses platters and actuator arms. Even SSD's can't compete with the speeds RAM provides. 

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?

So, what does RAM speed do? The speed of RAM is a tricky subject and one that actually comes down to several different factors and not just the Mhz clock speed. To get a real sense of how fast our RAM is, we need to take into consideration the CAS latency and clock speed simultaneously.

Clock Cycles (RAM MHz)

RAM frequency works off of clock cycles (people often call this the RAM speed even though it is 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 3.2 billion 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. There's usually a direct correlation between higher DDR (Double Data Rate) RAM and the clock cycles those modules accommodate. This can easily be seen when comparing DDR3, DDR4, and now DDR5 (Due to release end of 2019).

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.

Your memory timings determine how fast your RAM will respond to a command. However, faster MHz RAM with slower CAS timings might be slower than lower MHz RAM with faster CAS timings.

Finding Your Real RAM Speed

Finding the real speed of your RAM comes down to a couple of factors, and has been embodied in a handy little formula. However, before we show you the formula, let's understand the different factors to consider when finding your RAM speed.

The first factor is the RAM clock speed; let's take 3200Mhz as an example.

The next factor relates to what RAM you have. For example, DDR (Double Data Rate) transfers data on both sides of the clock cycle. Meaning, it transfers data twice in 1 cycle.

Then you have your timing, for which we will be using seconds.

And lastly, your RAM CL Timing, which is the first of the four numbers that make up the RAM timing. We'll use (14-15-15-39) for this example.

Those are the factors, so let's put that into an equation to work out the exact RAM speed.

(14*(1/(3,200,000,000/2))) = 0.0000000088 seconds = 8.8 nanoseconds

You can use this formula to work out exactly how fast any RAM you buy is, so it's a great little tool to have.

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 overclock your RAM to manufacturer-specified settings automatically.

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.

It's always a good idea to make sure all of your hardware is compatible with each other.

Can I Mix RAM Speeds?

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

RAM itself is compatible with other RAM of different timings and speeds. This being said, the greater the gap between the two speeds, the greater the stress your motherboard is going to incur 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 pick the slowest one and run them both at those speeds.

The further away you get in speeds and timings, the harder your motherboard is going to have to work to run them together. Furthermore, 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 complex topic that’s deserving of its own article (something we might 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.)

AMD APUs And Fast RAM

As many will know, the new batch of AMD processors is about to hit the market. So, we thought it would be suitable to touch upon how FAST RAM boosts the performance of these processors and why.

Let's start with their APU range.

An APU is the combination of a CPU and a GPU in one small package. AMD & Intel have been designing APUs for years now, allowing customers to get a slice of both pies at a hugely reduced rate. But how does an APU utilize faster RAM?

We must first learn how an APU works. Unlike a PC that has a freestanding GPU, the APU has the graphics integrated into the CPU. One of the benefits of having a standalone GPU is that it has its own, super quick onboard VRAM memory to go to when processing graphics. The APU, on the other hand, has to utilize your computer's main DRAM that will simultaneously be running the rest of your PC.

So, having quicker RAM, 3200+ will allow your RAM to able to accommodate both your PC and the integrated graphics at the same time, meaning you will see clear performance gains.

With their CPU range, it's a slightly different story.

Since Ryzen was released, AMD has been making use of its impressive multi-threaded nature. Multi-threading is when a CPU can double its cores by making use of virtual cores. If your CPU has six cores, it would have 12 threads, and so on. This being said, each thread will try to access your RAM, meaning quicker RAM will be more suitable to accommodate a multi-threaded CPU over say, an Intel CPU that doesn't have this facility.

We're currently in the process of putting together some benchmarking results of AMD vs. Intel and how faster RAM affects them in real-world situations. Stay tuned to see those results soon.

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 RAM speed 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, only really 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 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 RAM speeds benefit you, is when you’re doing multitasking like running multiple programs or streaming while you game.

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.