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0 pointsreissbaker5y ago0 comments

I've read various theories about the right memory clock speed to use for Zen, but in all the gaming benchmarks I've seen, faster RAM clock speed ends up resulting in higher performance.

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scottlamb5y ago

> I've read various theories about the right memory clock speed to use for Zen, but in all the gaming benchmarks I've seen, faster RAM clock speed ends up resulting in higher performance.

Got citations? Better yet if there are any developer-oriented benchmarks.

I'm building a Zen3 machine to use as a workstation. I just ordered DDR4-3600 RAM (but can still probably change the order if I made the wrong call). The specifications [1] only mention 3200 Mhz, so I think even that is overclocking the I/O chiplet to run at 1:1. I want a stable development machine rather than a toy so I wasn't planning to go further.

I also read an interview [2] (most interesting part quoted below) which suggests there's diminishing utility in going beyond 3600.

> Okay, so what’s the best price/performance?

> DDR4-3600 continues to be a “sweet spot.” The kits are inexpensive, widely available, perform well, and have good compatibility. Is it the best in every category? No, but that’s not what the sweet spot is. 3600 is a good bet because it’s a good value in perf/$ for someone who wants to plug and play. Is it the best possible performance? No. Is it close? Yes, and without tinkering.

> What’s the best memory, even if i have to overclock?

> Probably very tight timing 3600 or 3800, just like the Ryzen 3000 Series. The timings on these memory bins can be super aggressive versus higher memory speed grades, and that usually overpowers frequency.

My RAM is actually CL18 DDR4-3600. Maybe I should have gone with CL16...I'm not sure how much it really matters for development though, and I'm getting 64 GiB of RAM so the cost per byte adds up a bit more than it does for a gamer buying 16 GiB.

[1] https://www.amd.com/en/products/cpu/amd-ryzen-9-5950x

[2] https://videocardz.com/newz/amd-robert-hallock-promises-ryze...

reissbakerOP5y ago

Here's one side-by-side you can watch with the same games being played on the same Zen-based system, but with varying RAM clock speeds: https://youtu.be/8H0DEkpEDCE Generally, the highest-clocked RAM got the best average and min FPS in the games tested.

I'm having trouble finding it now, but IIRC I also once saw a side-by-side comparing different RAM latencies, and the differences were not enough to outweigh clock speeds; i.e. overclocking with worse latencies was better than lower latency but lower clock.

That being said I've seen non-gaming benchmarks that imply that there is a 3600mhz sweet spot. So it may vary based on workload. I haven't looked into that closely though — I was looking at benchmarks when building a gaming PC, so I had a specific focus :)

eloff5y ago

Especially true with Zen 3.

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