Hi, I wanna build a PC with
AMD Ryzen 7900X
4x32GB of memory
AMD Radeon 7900XTX

however I am not sure which memory I should use. If something like Kingston Fury DDR5 5600 CL40 KF556C40BBAK2-64 (x2) is appropriate or what is the best kit/max speed at which I can run? I don’t want to really tinker with memory timings afterwards since it’ll be a production machine.

I have 128gb with 2 kits of KF556C40BBK2-64 on a proart x670e and 7950x

I am using 4200cl40-40-40 1.25v

It will boot into windows at 1.35v 4600 and just fails memory test not bluescreen. It weirdly also had memory errors at 1.35v 4400 so I just set it to 4200 and left it.

I am not sure what a safe higher voltage would be to try get 4400 or 4600 stable
I was able to get into the bios at 4800 1.35v. Could be possible if 1.4-1.5v was safe but I don’t know.

wow, that’s a huge stepdown, did you also test a single kit? and any benchmark to compare? I am curious how the performance falls off at these speeds

No sorry I didn’t do a test with 2 dimms. Benchmarks were all close to what reviewers were showing. I was only checking to make sure I didn’t have anything misconfigured but I didn’t write anything down. I don’t think there’s any performance falling off a cliff below a certain number its more like low single digit performance changes. Unless I’m mistaken but thats just from seeing my own results. I saw there was no feeling in performance and gave up and stuck to 4200 so I could just get to work

With 4 dimms you’ll likely not even get 4800 with the most high end of kits

If you need a lot of ram seek z790, wrx80 or epyc platform

This is probably none of my business but what even is your use case for that? I mean do you have any idea what your power draw will be?

This build better make you money because the operating cost requires that you pass down cost elsewhere…

analytics in python/devops by day, gaming by night
power draw should still be better with amd+amd than intel+nvidia, but yea, i know it won’t be cheap, still better than azure or some kind of cloud instance

thought the speed should be a matter of CPU that not the RAM kit itself, i can buy 5600Mhz but if the CPU memory controller can’t handle it than it’s probably not worth spending extra

They type of memory chips can make it easier

That’s why every wanted Samsung b die early in ryzen

Are there examples of z790 doing much better on this? Fwiw from what I’ve seen so far, they also can’t run 4x32 stably beyond 4400-4800 (maybe 400Mhz or so higher than AMD though).

I can’t remember the type of chip is the beesknees but I believe it’s not Samsung

Yeah I think Hynix is the goat this gen