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My team and I are considering the purchase of a new compute server. Specifically we are dealing with CFD (Computational Fluid Dynamics) in the area of Space Engineering.

According to past experiences, as the codes we work with are in-house (not commercial like Fluent, OpenFoam, etc...) these are not optimized to the best, both because we are not programmers and because we use OpenMP to parallelize, without having strong parallelization infrastructures like MPI.

All this is to say that our main target are good CPUs with high frequency, very fast in terms of floating point operations. However, being many in the group, we need a good number of cores (between 24 and 32).

We already own two servers, one with Intel Xeon Gold 6248R and one with 6342 (both dual socket, such as will be the new one). We were considering switching to AMD CPUs, specifically we are considering Epyc 9374F and 9474F, chosen after discarding the Xeon 6458Q option (we do not own liquid cooling facilities).

My main concern for switching to AMD lies in the fact that we are historical users of the Intel Fortran compiler. I wonder if there is a big penalty in using that compiler in AMD architectures. Yes, I know AOCC exists, but not everyone in the group is willing to change habits (starting with simple compiling flags).

Can you tell me if the CPU choices are suitable for our purposes and whether possibly it is wrong to keep ifort as the compiler?

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iFort often performs reasonably well on AMD especially for recent models, couple things to note when using AMD for iFort avoid using specific intel optimization options like /Qx are tied to Intel-specific features and can hinder performance on AMD. Consider using /mavx on newer AMD CPUs so you can leverage their instruction sets if your code benefits from it. Use the appropriate -m flag like -mavx or -msse3 to match your AMD CPU's architecture. Avoid -x and -ax options as they might not work correctly.

You also might Consider exploring the native AMD Optimizing Compiler (AOCC) for potentially better performance and optimization on AMD CPUs. There are also Some Open Source alternatives such as Gfortran or Open64

TLDR: While ifort works on AMD, native compilers or alternatives might offer better performance or compatibility in the long run. Testing and evaluating your specific needs is key to making an informed decision.

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I do not think you will find 4 socket AMD cpu servers like you will with Intel Xeon servers. Such as a 4-socket Dell r940. I would start looking here... https://www.dell.com/en-us/shop/dell-poweredge-servers/poweredge-r940-rack-server/spd/poweredge-r940/pe_r940_12229_vi_vp

and look at https://ark.intel.com/content/www/us/en/ark.html#@PanelLabel595 for cpu's with frequency and # cores to meet your needs, sort by total cores or base freq. Xeon 8268 - 24c @ 2.9ghz base freq. A 4-socket server would provide 96 total cores @ 2.9 ghz base freq; or the 8256 cpu has the highest base freq @ 3.8ghz but would then only be 16 total cores.

you should be asking your question directly with Dell, HP, etc. and since you said codes we work with are in-house you should request them to benchmark your code on an AMD cpu server vs an Intel cpu server to see the difference. They can also provide benchmarks running commercial codes such as Fluent.

Can you tell me if the CPU choices are suitable for our purposes

not really, I don't know what codes you are running, how they scale to big problems, and what size problems you intend to be solving. It will be this as to what determines whether a 4-socket server, or 8-socket (lenovo, supermicro) is worth it vs a high density 2-socket AMD based server. The codes & compilers will run the same on either, you will want the intel ifort not for intel/amd chipset but for compiling the inhouse codes (that were written 30+ years ago in f77 which won't compile with gfortran or pgi)

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