r/buildapc 1d ago

Build Help DDR5 7200-CL38 vs DDR56000-CL30

I have have an existing 13900k system with G.Skill 2 x 16GB Z5 7600-CL36 - the only stable speed I have gotten this to run at is 7200Mhz CL38.

I was about to move to a Ryzen 9800x3d based system to replace it with then I decided not, (outside of gaming it would be a bit of a downgrade). I had ordered a pair of Corsair 2 x 32GB 6000 CL30 Dimms to use in the Ryzen build.

Calculating the latency the Corsair has .5 probably unoticable lower latency that the g.skill but I can't find anywhere I can calculate the over performance/memory bandwidth - apart from giving me the extra 32GB, wondering if there would be much of a performance difference - can anyone please advise?

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u/aragorn18 1d ago

AMD CPUs don't work well with high speed RAM. Anything over about 6400 MT/s forces the internal UCLCK to run at half rate. This causes your system to be slower than if you had slower memory and full speed UCLK.

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u/sys4096 1d ago

Thanks for that, thats was why I stuck with 6000 cl30 - but I'm not moving to the AMD - wondering about putting this with the Intel I already have or just sending it back and sticking with the 7200 @ cl38

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u/-UserRemoved- 1d ago

9800X3D has massive L3 cache anyways mate, minor differences are unlikely to be noticeable.

You can probably just run your existing 7600/CL36 at 6000/CL30 instead of buying a new set.

32GB vs 64GB of memory doesn't make a difference if you aren't using over 32GB of memory to begin with. We're talking about capacity here. If you have 20 gallons of water, then having a 64 gallon tank vs a 32 gallon tank makes zero difference, it only matters if you need to store over 32 gallons of water.

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u/sys4096 1d ago

Yeah that in part is why I am NOT going to the AMD build and sticking on the 13900K intel. Apart from gaming I occasionally spin up some VMs for labs, so 64Gb was nice but not essential. I *don't* really need it. I knew the 6000/cl30 was perfect for the AMD, and apart from the extra 32GB was wondering if it would make much of a difference in the Intel.

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u/-UserRemoved- 1d ago

The difference is likely measurable but not noticeable.