RAM write speed or L3 cache? eg.5800x or 5700G?

Maxmillian · April 28, 2023, 05:37

I'm looking for an upgrade for my R5-3600 CPU,
running 2x16G ddr4 3800mhz.

For AMD Ryzen's special design, the RAM write speed will be cut to half on a single CCD CPU(such as 5800x 5700x or 5600, less than 12cores), but their APU uses another structure so the RAM's write and read speed is identical.

CFD is memory bandwidth sensitive, but for read or write or both?

I'm looking at 5800x or 5700G, almost the same price, same 8 cores.
5700G could run faster RAM, but half the L3 cache(16mb to 5800x's 32mb)
Could anyone tell that which one will run faster for CFD?

Thank you

flotus1 · April 28, 2023, 06:29

Reads matter more. That's one of the reasons why AMD dared to to make the pipeline asymmetric, even on Epyc CPUs.

5700G vs 5800X is a no-brainer: The 5800X is much faster.
Though if you are shopping for the fastest possible AM4 upgrade anyway, consider the 5800X3D. It's overhyped and thus overpriced. But for CFD in particular, the extra L3 cache is worth it IMO.

April 28, 2023, 05:37	RAM write speed or L3 cache? eg.5800x or 5700G?	#1
Maxmillian New Member Fukai Ren Join Date: May 2020 Posts: 2 Rep Power: 0	I'm looking for an upgrade for my R5-3600 CPU, running 2x16G ddr4 3800mhz. For AMD Ryzen's special design, the RAM write speed will be cut to half on a single CCD CPU(such as 5800x 5700x or 5600, less than 12cores), but their APU uses another structure so the RAM's write and read speed is identical. CFD is memory bandwidth sensitive, but for read or write or both? I'm looking at 5800x or 5700G, almost the same price, same 8 cores. 5700G could run faster RAM, but half the L3 cache(16mb to 5800x's 32mb) Could anyone tell that which one will run faster for CFD? Thank you

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April 28, 2023, 06:29		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	Reads matter more. That's one of the reasons why AMD dared to to make the pipeline asymmetric, even on Epyc CPUs. 5700G vs 5800X is a no-brainer: The 5800X is much faster. Though if you are shopping for the fastest possible AM4 upgrade anyway, consider the 5800X3D. It's overhyped and thus overpriced. But for CFD in particular, the extra L3 cache is worth it IMO.