The story of AMD’s Zen CPUs and memory speed has been a complicated and often frustrating one, with early CPUs and motherboards being highly unoptimized when it came to memory support.
Running your memory faster than 3000MHz on 1st-gen Ryzen systems originally required very specific memory dies, or you’d be stuck at 2933MHz. It took several months and a few BIOS updates before we could run most memory at high frequencies on the first Zen chips.
That was unfortunate, because memory speed is very important with Zen CPUs, whether it’s an AM4 Ryzen chip or a Thread ripper processor. All these chips have a high-speed interconnect, otherwise known as Infinity Fabric, which is directly related to memory speed.
This in turn impacts on the performance of the CPU, sousing fast memory can make all sorts of software, from games to content creation, run faster.
The Zen2 architecture introduced a better memory controller, along with a stack of motherboard AGESA code tweaks from motherboard manufacturers, and 3rd-gen Ryzen CPUs are now happy to run memory at 3600MHz memory speed while maintaining a 1:1 ratio with the Infinity Fabric.
Go above this frequency, and some motherboards will start to use dividers, knocking back the Infinity Fabric clock, but allowing for faster memory to be used. In short, you should aim for a RAM frequency of 3600MHz or below, especially as memory prices can rocket above this speed.
For AMD’s standard AM4 Ryzen CPUs, we recommend 3466MHz memory, as it performs closely to 3600MHz RAM, while offering a decent gain over 3200MHz memory.
Is the same true for 3rd-gen Thread ripper? To find out, we tested the Thread ripper 3970X with a quad-channel Corsair Vengeance RGB Pro kit clocked at 2666MHz, 3200MHz, 3466MHz and 3600MHz.
As you can see from the results, 2666MHz should be avoided with these high-end systems, as it hammers performance in nearly every benchmark, especially games and multi-tasking, while it was 15 per cent slower than 3600MHz memory in our video encoding test too.
Stepping up to 3200MHz saw the frame rate in Far Cry 5 recover to almost normal levels, leaping from a 78fps minimum to 88fps.
However, moving up to 3466MHz saw a 6 per cent improvement in the video encoding test and 5fps added to the average frame rate in Far Cry 5, along with a substantial rise in multi-tasking performance.
The final notch up to 3600MHz did yield a noticeable boost to the video encoding score of around 8 per cent, but Far Cry 5, multi-tasking, Cinebench and image editing saw meagre gains Best WiFi 6 Routers .
Overall, the situation is much the same as with AMD’s mainstream 3rd-gen Ryzen CPUs. Memory speeds below 3000MHz should be avoided, as they rapidly see huge drops in a number of tests.
If you find a particularly good-value 3200MHz kit, you won’t lose vast amounts of performance, but considering you’re spending a sizeable amount on your system already, moving up to 3466MHz is absolutely worth the extra money Best Rolling Camera Bags.
Going up to 3600MHz only gave us a notable improvement in one benchmark. Plus, as most 3466MHz memory kits will overclock to 3600MHz anyway, this being Custom PC, we’d much rather tweak the BIOS and save some cash, so 3466MHz is our recommendation.
However, if you find a 3600MHz kit going cheap, it will still offer a small performance improvement without the hassle of overclocking.