When choosing components for a new build, RAM often gets overlooked in favor of the CPU and GPU. That makes sense, as the latter two generally have the biggest impact on performance. But your RAM has a significant role to play, too. If you want to get the best out of your rig, you need to know how to choose RAM.
From RAM speed to latency by way of RAM capacity and channels, choosing RAM can be daunting at first. But once you know what to look for, it’s not so bad. Let’s get going, shall we?
How Much RAM Do You Need?
The most basic question you need to address first is how much memory you actually need. There’s no one-size-fits-all answer, and the amount you need will depend directly on the sort of tasks you want to do on your computer.
If you’re building a gaming PC, 16 GB of RAM is preferable. 8 GB of RAM is generally acceptable too, and it likely won’t hold you back in most (if not all) titles. Either way, you definitely want to avoid going with a single 4 GB memory module. Not only are games starting to demand more than 4 GB of RAM, but you’ll also lose out on dual-channel RAM (more on this later) with 4 GB.
Battlefield V, for example, shows a significant performance gap between 4 and 8 GB of RAM. The 1% lows, in particular, are horrible with 4 GB of RAM at both 1080p and 1440p. Even if the average framerates aren’t that different, the significantly worse 1% lows will make for a much more stuttery and uneven experience.
What Are 1% and 0.1% Lows?
Gone are the days when a game’s average framerate was the defining metric. Instead, measuring a game’s 1% and 0.1% lows has become much more common. The 1% and 0.1% lows provide a better overall picture of the gameplay experience by showing the average framerate during the benchmark scenario’s worst moments.
Ideally, you want the 1% lows number, in particular, to be as close to the average framerate as possible. This indicates a smooth experience without major hitching or stutters. A large gap between the 1% lows and the average framerate shows that there will be significant stutters that will impact your experience significantly.
These periods of low framerate may not last for long enough to bring the average framerate down, but you’ll still feel them all the same. That’s why the 1% low number is particularly important.
Ubisoft’s The Division 2 is another game that struggles with 4 GB of RAM, posting significantly worse 1% lows with the lower capacity.
It’s worth noting that a mixed-capacity 12 GB setup (one 4 GB stick and one 8 GB stick) performs worse than matched pairs in the 8 GB (2×4 GB) and 16 GB (2×8 GB) configurations. Not drastically, but we recommend a matched dual-channel kit in either 8 GB or 16 GB capacities if you want the best performance possible.
We think 16 GB is the optimal amount of RAM in 2021, but 8 GB is still okay if you’re on a tighter budget. You can always upgrade later anyway since RAM’s probably the most straightforward part of a gaming PC to upgrade.
How much RAM you’ll need for productivity and professional tasks will depend entirely on your workloads. We can’t cover every single workload here, but let’s take video editing as an example.
The amount of RAM that a frame of video increases significantly with resolution. 480p, 720p, and 1080p don’t use up much RAM. However, once you hit 4K and above, the RAM usage spikes, as you can see here:
So, it stands to reason that the higher the resolution of your video files, the more RAM you’ll need. If you’re only editing 720p and 1080p videos for YouTube, you’ll probably be able to get by with 16 GB. However, suppose you need a rig for intensive professional work with multiple high-resolution HDR video files. In that case, we’d recommend 32 GB as a minimum.
Some workloads will require more RAM than others, so you’ll have to do some research to see whether your particular task will benefit from more than 16 GB of RAM.
The only time 4 GB of RAM might be OK in a desktop PC is if you only need it for basic tasks like web browsing, casual browser games, and email. It’s not ideal, but you’ll probably be able to make it work.
That said, the memes about Chrome gobbling up RAM aren’t a joke, and it’ll happily eat up 1 GB or more depending on how many browser tabs you have open. Add that to Windows’ background tasks and any other open programs, and you might find that you hit the 4 GB limit surprisingly quickly.
So if you (or the person you’re building the computer for) like to open up multiple tabs when browsing, consider stretching your budget to accommodate an affordable 8 GB kit. This Patriot Signature 8GB 2666MHz kit is well below $50 and is worth checking out for a casual-use computer:
Single vs. Dual Channel
RAM communicates with a CPU via dedicated channels that are somewhat tied to the number of RAM modules installed. A single stick means a single-channel setup, dual sticks means dual-channel RAM, and so on.
To put it simply, you want a dual-channel RAM setup. No ifs and buts here, especially not if you’re using Ryzen. AMD’s recent CPUs really like memory bandwidth, to the point where even gaming performance will suffer if you only have a single stick of RAM.
Case in point, check out Jarrod’sTech’s comparison between single- and dual-channel RAM in Red Dead Redemption 2 at 1080p. If you’re even remotely serious about wanting to game, you owe it to yourself to make sure you’re using a dual-channel kit.
Of course, not every game will show such significant differences between single and dual-channel RAM. The performance gap also tends to reduce at higher settings or resolutions. But the differences are there and, in many cases, are significant.
And it’s not just gaming, either. While RAM capacity may not have a massive impact on rendering times, dual-channel RAM certainly does. Your mileage will vary, but we wouldn’t be surprised if the 30- to 40-percent improvement seen here is replicable across different setups and presets.
If you’re worried that the extra RAM stick will wreak havoc on your budget, fear not. Prices for equally-specced single- and dual-channel kits aren’t too dissimilar. Yes, dual-channel memory kits tend to be a bit pricier. However, we think the significant performance improvement is well worth the slight price increase.
Curious about adding more than two RAM sticks? Check out our guide to dual-channel vs. quad-channel RAM.
RAM Speeds and Latency
This is where learning how to choose RAM gets a bit nerdy. This is a complex topic that we could spend an entire article discussing. This will only be a very surface-level discussion, but one that hopefully gives you a good enough idea of what to look out for.
Interested in digging deep into RAM latency and timings in particular? GamersNexus’ article on the topic is a decent place to start.
Explaining MHz and CAS Latency
After you’ve figured out how much RAM you need and the configuration you want it in, it’s time to think about RAM speeds and CAS latency. RAM speed is self-explanatory: it’s a measure of how much data a kit can transfer in a second. RAM speeds are conventionally quoted in Megahertz (MHz).
The “2666 MHz” mentioned in the product names for the HyperX RAM kits above are the kits’ speeds. Technically, higher is better, but not every program or workload benefits from faster RAM.
CAS latency is a bit more complex. CAS stands for Column Access Strobe (or Signal) and measures how quickly a memory kit can process data and provide it to a CPU when requested. Lower numbers are better when it comes to latency. That said, not all programs will benefit from lower latency. More on this later.
Let’s take this 3600 MHz G.Skill kit as an example:
The CL16-19-19-39 listed in the product listing means that this is a CL16 kit. CL16 3600 MHz indicates quite a high-end product; most RAM kits will likely run default timings closer to CL18. Generally, anything CL18 or below is quite acceptable.
Also, remember to enable XMP in your motherboard’s UEFI settings. If you don’t, your RAM will run at its standard JEDEC speeds, which are lower than the RAM’s advertised speeds. Enabling XMP is different for each motherboard, but here’s what it looks like on a Gigabyte B550 motherboard:
Now that we’ve gotten the explanations out of the way let’s look at how these two settings impact performance.
Performance Impact of Speed and Latency
The performance improvements you can get from increasing memory speed or reducing latency aren’t always significant or worth the extra cost or time spent overclocking. However, when a program does benefit from faster RAM, the differences can be quite impressive.
Let’s take Fortnite as an example. Tests have shown that just enabling a RAM kit’s default 3200 MHz XMP profile offers up 19.9% improved 0.1% lows and 8% improved average FPS. This is compared to the default, non-overclocked speed, which is likely around 2666 MHz.
Pushing the RAM further with either higher speeds or reduced latency (or both) sees some impressive gains, too, topping out at 431 FPS average with 4200 MHz CL16-17-17-35 RAM. If you’re a hardcore Fortnite player, faster RAM might be worth it.
The ever-popular CS:GO, though, doesn’t show quite the same level of improvement. The most considerable difference comes from enabling XMP, which increases the 1% lows by about 5%. Everything after that first step is marginally better at best. There’s only a 6% difference in 1% lows between 3200 MHz CL16-18-16-35 and 4200 MHz CL 16-17-17-35; hardly worth the time, effort, and money chasing the faster speeds.
On paper, faster RAM and reduced latency are always better. But as you can see with our two examples, you won’t always see real-world benefits in the games and programs you use. The RAM speed you go for comes down to the programs you use and how much you can afford to spend.
Recommending RAM speeds to look out for is a challenging task, as so much of it depends on the CPU and chipset you’re using. For any recent Ryzen or Intel CPUs on high-end chipsets (Z-series for Intel, X570/B550 for AMD), 3600 MHz CL18 or lower is probably your best bet.
You can go faster if you really want, but remember to stay below your motherboard’s maximum supported speed, or you’ll just be wasting money. Using an older CPU or a lower-end chipset? Get the fastest RAM that your motherboard supports with the lowest latency you can afford.
You can find a motherboard’s supported RAM speeds in the manual or on the manufacturer’s product page, like so:
Either way, don’t overpay for your RAM! Yes, tighter memory timings and lower latency can increase your FPS, but you shouldn’t be worrying about timing and speeds until you’ve made sure the rest of your rig is up to par. Before worrying too much about how fast your RAM runs, prioritize the best CPU and GPU you can afford.
Installation and RAM Clearance
We mentioned this earlier, but it bears repeating here. RAM is one of the easiest components to upgrade, so don’t worry if you can’t install as much RAM as you would like due to budget constraints. If money’s tight and you have to choose between 16 GB of RAM and a slightly better GPU or CPU, choose the latter.
This brings us to another critical aspect of choosing RAM for your rig: clearance. Depending on the CPU cooler you use, you may find that there isn’t much clearance for the memory modules on your motherboard.
While AMD and Intel stock CPU coolers won’t pose any issues, aftermarket tower coolers can pose a few more problems. That said, it depends on the type of tower cooler you go for. Single-tower coolers designed for lower heat loads, like the Noctua NH-U12S, won’t obstruct any of your RAM slots. This means you’re free to install taller RAM modules as you please.
However, big boy dual-tower coolers like the be quiet! Dark Rock Pro 4 will be a bit more challenging. These are designed for hot, high-power CPUs and need the extra mass to keep temperatures in check. These will obstruct some, if not all, of your RAM slots and severely limit the height of RAM you can install.
Most of these coolers will allow you to move the front fan up to increase RAM clearance. This, however, increases the cooler’s total height. Depending on your case, you may find that moving the fan up for RAM clearance means it ends up interfering with your side panel.
So, if you want to use a Dark Rock Pro 4 or any other dual-tower air cooler, we suggest looking into one of the best low-profile RAM kits to avoid clearance issues.
Note that this note about RAM clearance only applies to air coolers. Liquid-cooled AIOs only have a small pump block above the CPU, so your motherboard’s memory slots will be unaffected. Want to install a flashy set of G.Skill Trident Z Royal RAM with your AIO CPU cooler? Be our guest.
Figuring out how to choose RAM can appear quite challenging initially, but it’s not nearly as complicated as it seems. Sure, there’s a lot of complexity under the surface, especially if you want to get into RAM timings and overclocking. Still, most users can safely ignore that info and get by with their RAM’s standard XMP profile.
The amount of RAM you install and its speed will depend heavily on your budget and programs. 16 GB of 3600 MHz CL18 (or CL16) RAM is arguably the sweet spot for a modern gaming rig, but you can go higher or lower depending on your needs. However much RAM you do end up installing, though, make sure you use two matching memory modules for dual-channel mode.
Need advice on choosing other parts of your new rig? You can check out our guide to picking PC parts for more info and links to further in-depth guides.