Here at Numerion we are always on the look out for the latest top performing CPU for Carbon simulation.
For the last couple of years its been the Zen 2 based 3970X, but with the arrival of the Zen 3 architecture we were hoping for a HEDT Zen 3 equivalent. However in the absence of competition from Intel, AMD decided not to bother producing HEDT and only produce the $3,500, 5975WX Threadripper Pro version. Sucks, but hey that's life.... Also they delayed the general release until a couple weeks ago.
Ok so needless to say, even though the PRO version is more expensive and slightly slower than the HEDT would have been, we still wanted to check it out- short summary, its better, but not amazing.
First, importantly, if you want the best Carbon simulation performance you have to jump in the bios and:
1) turn off virtualization
2) turn off SMT
each of those can easily cost 10% performance.
AND WITH THE 5975WX it appears you MUST also have all 8 memory dimm sticks installed.
Carbon is not very sensitive to main memory bandwidth, but we think there is some explicit mapping between memory channels and cores on Zen 3, and that means you run 45% slower if you only have 4 sticks installed!
Note this is very different to the 3970X where for Carbon, 8 sticks is only 2-3% faster than 4 and IMO not worth the extra cooling requirement for a fully populated memory.
Ok I hear you asking, but how much faster was the 5975WX than the 3970X? Well in our initial tests its about 15% faster where both have all 8 memory dimms installed. About the minimum we expected from the improved cache architecture and higher IPC count.
There are also a lot of cache and memory options in the bios ( ASUS Pro WS WRX80E-SAGE), maybe there is a tweak to extract even more performance. We will keep tweaking and report if we find anything significant.
Meanwhile happy simulating.
