[diogoperdigaodp]

Hey there.

I'm building a new PC for CFD work in University, since I only have a laptop.
Because I don't know much about hardware requirements for CFD, I would like some help.
I would like to choose between these (although I'm open to suggestions):
Ryzen 5 5600X
Ryzen 7 5700X
i5 10400
i5 11400
i5 12400
i5 11600
i5 12600
i7 11700


Is 64 GB of ram worth it over 32 GB?


Thank you!

[wkernkamp]

The best Ryzen is benchmarked here:

Originally Posted by Simbelmynë

5800X3D, 2 x 8 GB DDR4 Rank1 @ 3200 MT/s (14-14-14-14-28,1T)
OFv9, OpenSUSE Tumbleweed, GCC 11.2, kernel 5.17.4

The 1 core result is amazing and the 6 core result is pretty decent as well. I assume this is the fastest dual channel CPU for CFD right now. Well at least until someone with a large wallet can post some results for Alder Lake with DDR5 @ 6400+ MT/s EDIT: (missed the post a couple pages back, the i5-12600 with DDR5 @ 6000 MT/s is indeed faster, and not terribly expensive with a B660 motherboard, so definitely a better value if buying an entire new computer)
The single-core result is 33% faster than the 5900X (from this thread). The 5900X has a single core boost up to 4.8 GHz while the 5800X3D only boosts to 4.5 GHz. Apparently the extra V-Cache is more important than the extra single-core speed.

 cores       Simulation     Meshing
#                (s)      (min.sec)
1             314.21        12m23s
2             201.98        8m21s
4             149.98        5m05s
6             138.55        4m02s

Will update if I manage to push the memory and IF to 1800 MHz.



EDIT:
2 x 8 GB DDR4 Rank1 @3800 MT/s (16-16-16-16-32, 1T)

cores    Simulation         Meshing
#           (s)             (min.sec)
1            304              12m14
2            188              8m12
4            135              4m58
6            124              3m55
8            122              3m28

I have some results where the IF manages 2000 MHz, which admits 4000 MT/s in 1:1. Not fully stable though so i need a few more days to learn this particular CPU. The interesting part is that higher IF speeds means that the L3 cache latency decreases, so it not only admits higher bandwidths.

[wkernkamp]

The best Intel is benchmarked here:

Originally Posted by ErikAdr

The version openfoam2112 did not provide an executable of 'surfaceFeatures' and that was why I could'nt get any results for the motorbike benchmark. I gave up on openfoam2112. I went for a go with version 9 from openfoam.org. First I installed ubuntu 20.04.3 (standard installation) and then I followed the guide from openfoam.org to install on ubuntu. Next I downloaded the 'bench_template.zip' in post 447 by Simbelmynë and then I followed the guide from step 4 to 7 in post 448 by linuxguy. Everything worked in first attempt. That was a strange feeling after the many previous attempts.



I have build a quite low end computer, but with quality components. It is using a i5-12600 cpu with two channel DDR5 Ram. I'm pleased with the performance.



12th Gen Intel(R) Core(TM) i5-12600 DDR5 @ 4800

# cores Wall time (s):
------------------------
1 427.45
2 234.12
4 149.91
6 125.75



12th Gen Intel(R) Core(TM) i5-12600 DDR5 @ 5600

# cores Wall time (s):
------------------------
1 410.79
2 219.95
4 137.39
6 112.58

12th Gen Intel(R) Core(TM) i5-12600 DDR5 @ 6000

# cores Wall time (s):
------------------------
1 399.94
2 213.75
4 131.87
6 107.09

[wkernkamp]

The amount of memory depends on problem size and code. I would go with 64GB.