I'm about to build a new rig featuring the AMD Ryzen 9 9950X3D CPU, which has a max memory speed of DDR5-5600 according to its specs. However, I keep seeing recommendations for 6000 MHz CL30 RAM as the optimal choice for AMD AM5 builds. I'm curious about where the idea of 6000 MHz being the 'sweet spot' comes from. Is 6000 MHz really the best option, and what's the logic or proof behind this claim? Can anyone explain?
3 Answers
AMD has rated anything above DDR5-5600 as 'overclocked', but truthfully, most AM5 CPUs can easily handle 6000 MHz. The reason they set it at 5600 might be to cover themselves against those rare CPUs that don't perform well under higher speeds. It's a bit of a weird situation! If you want a deeper dive into this, check out the Hardware Unboxed video on DDR5 speeds related to AM5 CPUs.
For best performance, go with the 6000 CL30 RAM and stick with two sticks. That way you’ll get the most out of your setup.
The reason for the 6000 MHz sweet spot is due to how DDR5 interacts with the FCLK. Beyond 5600, you’re often exceeding what the FCLK can maintain at a 1:1:1 ratio. When you hit 6000 MHz, it keeps your UCLK and MCLK in check with FCLK, resulting in a stable 3000:3000:2000 ratio. It’s theoretically possible to push FCLK closer to 2200 MHz for 6600, but that rarely happens practically. So, 6400 is sometimes pursued as a compromise if benefits are noted.
Don't forget there are also CL28 and CL26 kits if you can track them down—they can provide even better performance!