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Cross posted on StackOverflow.

I ask this question cause recently my department want to purchase a HPC cluster mainly for first principle calculation. For now we have three choices:

(1) Per node dual CPU processor (AMD EPYC 7543, 32 cores per CPU, 8 memory channels per CPU), 16 * 32 GB DDR4 RAM. Total 16 computing nodes.

(2) Per node dual CPU processor (AMD EPYC 9334, 32 cores per CPU, 12 memory channels per CPU), 16 * 32 GB DDR5 RAM. Total 8 computing nodes.

(3) Per node dual CPU processor (AMD EPYC 9554, 64 cores per CPU, 12 memory channels per CPU), 24 * 16 GB DDR5 RAM. Tital 8 computing nodes.

I am very hesitant about choosing between three options. The CPU processor in option (1) is a little old, the memory channels are not fully utilized for dual CPU processors in option (2), and the memory per core is only 3 GB in option (3). Each option has its own disadvantages. I am wondering which one would be better for running first-principles software such as VASP, CP2K, and QE. I hope someone could help me make a decision.

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  • $\begingroup$ Dear @Tieyuan Bian, you may find this mattermodeling.stackexchange.com/questions/7153/… useful for VASP RAM estimation . Concerning the comparison of the three setups, i don't have much experience on this topic, but i do have worked on EPYC 7502 (64 with hyperthreading). More cores per computing nodes results in great benefit in node-to-node comparisons, compared to smaller nodes (e.g. 32). Even tough i worked with fairly large systems (VASP), i never had memory issues. You should also consider that AMD nodes do not support AVX512 instructions. Hope this helps. $\endgroup$
    – Salvios
    Jul 24, 2023 at 10:28
  • $\begingroup$ Very thanks for your comment @Salvios . I agree with you since I have also made some tests comparing node containing different CPU processors. May I ask that what is the amount of memory per node of your EPYC 7542 cluster? $\endgroup$ Jul 24, 2023 at 11:02
  • $\begingroup$ Each node has two 32-core EPYC processor chips and 256 GB memory (4 GB * 64 cores = 256 GB), and a 2.5 GHz clock rate. The nodes i am using are probably an earlier version of yours since the memory type is DDR4. Here is the link to the AMD website for details amd.com/en/products/cpu/amd-epyc-7502. Indeed, you are probably looking at the last-gen of AMD processors. So, as a non-expert in the field, I would personally aim for more nodes. I think this might also be a suitable question for Stack Overflow since first principle codes are nothing but mpi-enabled CPU-intensive apps. $\endgroup$
    – Salvios
    Jul 24, 2023 at 11:59
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    $\begingroup$ Thanks for your reply @Salvios. I just asked this question on stack Overflow. Hope I can get valuable advice. $\endgroup$ Jul 24, 2023 at 12:18

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