[martinh]

Ryzen has just released its new Zen 4 CPUs, including the fastest 7950X.

Would you have any insights as to how these could help in CFD work particularly compared to its closest (workstation) competitors, particularly the AMD Threadripper Pros?

I've long been eyeing a 5965WX Threadripper Pro but this one costs $2300 and a compatible motherboard costs $1000 which is quite expensive. This one has 26 cores and 8 memory channels of DDR4 to feed those (my preferred machine would have 128GB of RAM at minimum).

At the same time the new Ryzen 7950X with 16 cores can be fed by 128GB of DDR5 memory. It has larger caches than its predecessor (e.g. 5950x) but at the same time with 128GB of RAM the base clock speed goes down to 3600 MT/s (I've seen some posts reaching 4200 after lots of struggling...) given that it has only 2 memory channels and you'd need 4 sticks of 32GB DDR5 RAM currently. So it seems only 50 GB/s of bandwidth in total in the end.... Would e.g. the larger cache alleviate some of this in this respect?

Also any chance of 64GB DDR5 memory sticks - with decent speed - coming in the future? AMD said the ideal would be 6000 MT/s for its CPU - so you could reach 128GB of RAM with about 120GB/s memory bandwidth at some point?

Highly appreciate all your insights - I am very new to this. Thank you!

EDIT: some SPEC benchmarks here:

https://www.anandtech.com/show/17585...he-high-end/12

And comparable benchmarks here for M1 Max:

https://www.anandtech.com/show/17024...mance-review/5

and Intel Xeon 3rd gen:

https://www.anandtech.com/show/16594...lable-review/6

[the_phew]

If you believe :https://openbenchmarking.org/test/pt...80ecda#metrics

the 7950x is an incredible value for OpenFOAM, being over twice as fast as the 5950x. The Threadripper Pro 5965WX is almost twice as fast again, which you would expect given the eight memory channels. However, I strongly suspect that those 7950x benchmarks were performed with 64GB of RAM or less, so the memory was probably operating at 'full' speed. If they had 128 GB of DDR5 installed, the memory speed would have dropped down to 3600 MT/s (DDR4 speeds)

If 64GB of RAM is sufficient for your simulations (rare in my experience), then the 7950x with two 32GB sticks of 6000 MT/s DDR5 should be killer price/performance. Otherwise, saving up for a 5965wx or 5975wx is probably your best bet. Even the 5955wx (16 cores and effectively cut down to four channels of DDR4) should outperform the 7950x with only two channels running at DDR4 speeds, but the 5965wx would be a big step up with double the effective memory bandwidth.

I wish the Threadripper Pro CPUs were priced more affordably. They really are the perfect desktop CPUs for CFD, but the prices are no cheaper than EPYCs. Until Intel decides to compete in the 'HEDT' market (like they did for years with the 'X-series'), AMD has no incentive to offer a price-competitive HEDT CPU lineup. There are rumors that Intel could re-enter that market with lower-end W-3xxx Xeons, which could inspire AMD to counter with 'non-Pro' Threadrippers. But I wouldn't count on it, since they print money using all their fab capacity to make EPYCs and 'WEPYCs' (Threadripper Pro).