Ryzen 9 3900X: does faster RAM improve gaming performance?

RAM speeds have historically been ignored by PC gamers, with most tests revealing such a small delta in performance that there was little reason to spend more on faster memory over upgrading other components. However, that slowly seems to be changing for a few different reasons. First up, high refresh rate monitors mean that gamers are seeking higher frame-rates than ever before. Here, the GPU stops becoming so much of a limiting factor and other system components - like the CPU and RAM - come to the fore.

AMD's Ryzen has also been complicit in the greater awareness of RAM speeds, as first and second-gen Ryzen were much more dependent on fast RAM than their Intel competitors thanks to their unique design. Communication between core complexes is limited by memory frequency, so forking out for high-bandwidth 3200MHz RAM became a sensible option. In 2019 with the launch of third-gen Ryzen, RAM prices have come down steadily and previously pricey 3000MHz or 3200MHz DDR4 RAM has become the new standard. AMD's guidance suggests that performance will continue to scale well up to about 3733MHz though, with 3600MHz kits becoming the new enthusiast upgrade option. That's why AMD provided us with 16 gigabytes of 3600MHz RAM for our testing, which turned out to be GSkill's ostentatious Trident Z Royal kit.

Regardless of its looks, 3600MHz RAM does provide a lift to in-game frame-rates. To quantify that boost, we looked at three games from our test suite: Ashes of the Singularity, Far Cry 5 and Crysis 3. All three games show very different characteristics as we compare the same RAM clocked at 3000MHz and 3600MHz. Ashes shows the Core i9 9900K and Ryzen 9 3900X both drop around five per cent, while Far Cry 5 shows a much smaller drop: three per cent for the 9900K and just one per cent for the 3900X. Finally, Crysis 3 is almost independent of RAM speeds on newer hardware, with the 9900K showing near-identical results and the 3900X only dropping by around three per cent; by comparison the 2700X is much more dependent on RAM speed and drops around 10 per cent in the same test.

We could spend much longer investigating how RAM speed affects game performance - it could be a feature in and of itself - but we'll call it there for now. The broad conclusions are that AMD is less sensitive to RAM speeds than its predecessor, but choosing a high-end kit still provides a measurable uplift in average frame-rates. It's also possible to overclock the Infinity Fabric that links different components on the chip beyond RAM speed, and testing elsewhere suggests this can partially make up for low RAM speeds. Either way, it's well worth experimenting if you're using AMD hardware. Meanwhile, Intel seems to better make do with slower RAM, but there are still small gains to be had here. One more point: Intel also restricts memory overclocking pretty severely unless you plump for a high-end 'Z' board, whereas AMD allows it on their mid-range motherboards as well. If you want to maximise performance for the money, AMD's platform could well be the better choice.

AMD Ryzen 9 3900X analysis

• Introduction, hardware breakdown, test system
• Gaming benchmarks: Assassin's Creed Odyssey, Battlefield 5, Far Cry 5
• Gaming benchmarks: Crysis 3, Metro Exodus, Kingdom Come Deliverance, The Witcher 3
• Gaming benchmarks: Ryzen vs Core - memory bandwidth analysis [This Page]
• Ryzen 9 3900X: the Digital Foundry verdict