When building a new PC or upgrading an old one, people often wonder about the memory or RAM size. But the questions on most people’s minds are “how much RAM do I buy?” and “how fast does my RAM need to be?” Both of these are valid concerns, to an extent. You need a minimum amount of RAM (at least 8 GB) to run modern games, well, at all. If you’re still stuck with 4 GB you will be encountering more and more hard exits at launch, simply because your system doesn’t have the resources to load large assets.
Impact of Memory Speed on Gaming Performance
RAM speed, in terms of frequency, can also have an impact on your gaming experience. The higher the frequency, the greater the memory bandwidth. With DDR4, 3200 MHz is the ideal target. A small lifehack: pick up low-clocked RAM from big-name manufacturers like Samsung. There’s a very high chance that you’ll be able to crank the clock speeds up on the modules.
I have 4 RAM modules–a pair of ADATAs at 2400 MHz stock and a Samsung module at 2100 MHz. All four happily run at 2933 MHz. High-frequency RAM is especially important if you have integrated graphics: your iGPU shares memory with the CPU and you’ll need as much memory bandwidth as you can get.
Single-Channel vs Dual-Channel Memory
But there’s a third concern that is often overlooked. And it has a far larger impact on memory bandwidth than overclocking your RAM modules. We’re talking about going dual-channel. What is a dual-channel memory config and what’s the difference between dual and single-channel configurations?
RAM communicates with the CPU through the memory controller on the CPU. Most modern motherboards have two 64-bit (total 128-bit) channels between the CPU and memory. In a single-channel configuration, only one of them is functional. This limits memory throughput to the rated speed of the slowest single RAM module installed.
In dual-channel memory configurations, the memory controller uses both the channels to communicate with the CPU, essentially doubling the bandwidth. But what about multi-channel configurations? Technically, quad-channel systems exist, but they’re mainly found on server-centric and exotic boards. For most people, multi-channel means dual-channel memory.
Dual-Channel Doubles Memory Throughput
Single-channel 2133 MHz DDR4 delivers 17 GB/s of memory bandwidth. If you have a pair of 2133 MHz DDR4 modules in dual-channel, your memory bandwidth doubles to 34 GB/s. The only way to hit that level of performance in single-channel mode is to use memory modules running at 4000 MHz or higher.
We have to stress an important point here: you need RAM modules in multiples of two in order to utilize dual-channel. Most budget to midrange boards will either have two or four memory slots. I have a Gigabyte B450 DS3H with 4 memory slots and dual-channel support. If you have two slots and your motherboard supports dual-channel, setting it up is often as easy as just inserting a second memory module and booting up.
If you have 4 slots, however, things are a bit more complicated. Your motherboard manual will tell you which slots to insert your RAM modules if you want to enable dual-channel. Or, you could just get 4 RAM modules and have it run by default. This can be confusing because there’s usually no “on switch” for dual-channel memory. As the Hardware Times motto goes, “it just works.” Well, at least when it does work.
If you’re not sure about whether or not dual-channel is enabled, download CPU-Z, then click on the memory tab. It’ll mention whether you’re running your memory in a dual or single-channel configuration.
Impact of Dual-Channel Memory on Gaming Performance: AMD Ryzen 7 3700X
What are the benefits of dual-channel memory? It can vary from game to game, but several titles show a significant increase in your minimum and average framerates with a dual-channel configuration. The Assassin’s Creed series and Fallout 4 are notable examples. Assassin’s Creed Origins and Assassin’s Creed Odyssey are nearly unplayable on PC without dual-channel memory.
As you can see, while the average frame rates aren’t affected by much, the lows and consistency take a big hit. The CPU latency in single-channel increases by a whopping 50%. This because there is only one 64-bit channel between the CPU and memory (in dual-channel, there are two 64-bit=128-bit)
Other games like The Division 2 and Shadow of the Tomb Raider see less of an impact but the frame pacing and minimum FPS see a significant drop.
In single-channel mode, the FPS drops 60 quite often but in dual, it stays over 60 throughout the duration of the benchmark. At first sight, dual-channel memory may seem like a minor upgrade it has a quite obvious impact on your overall gaming experience. The FPS drops are fewer and the 99% lows are particularly higher. This directly translates into smoother gameplay and fewer bouts of anger.
Impact of Dual-Channel Memory on Gaming Performance: AMD Ryzen 9 3900X
Let’s do a more detailed test, this time with the 12-core Ryzen 9 3900X. Unlike the Ryzen 7, the 3900X has two CCDs, connected by the Infinity Fabric. As such, the impact of memory speeds and dual-channel memory should be more prominent in this case. We’ll be testing Assassins’ Creed Origins and Ashes Escalation at the highest quality preset at 1080p (paired with an RTX 2080 Super):
As expected, Assassins’ Creed chokes really hard when using a 2400MHz, single-channel configuration. Even the mighty 3900X can’t hit an average of 60 FPS, with lows of just 20. That too at 1080p with an RTX 2080 Super to boot. Switching to a dual-channel config, more than doubles the lows and pushes the average to over 80 FPS. It’s interesting to note that a dual-channel 2400MHz kit is better than a single channel 3600MHz config.
Ashes Escalation shows similar results. The game is unplayable with a slower single channel config, but switching to a faster memory module or a cheap dual-channel kit does the job. Once again, a cheaper dual-channel config is better than a pricey single-channel 3600MHz module. At the end of the day, it’s about the overall bandwidth, and the former delivers more data to the CPU, all the while keeping your budget reasonable.
Going dual-channel is one of the simplest, most obvious upgrades you can make. You already have (at least) a single RAM module. You can double your memory bandwidth for the price of just one more, and increase your framerate in some games by as much as you would when getting a new GPU.
And if you’re gaming on integrated graphics–such as on a Ryzen APU–dual-channel memory can increase your average framerate in most games by 10-30 percent, or even more. It’s inexpensive, easy to set up, and delivers a notable boost to performance. Go dual channel. Just do it.