Workstation build for CFD
 

I am an undergraduate student, and this fall I will need to conduct CFD simulations for a paper I'm writing. As an undergraduate, they won't give me access to my uni's cluster, I could try cloud computing, but I rather have the flexibility of having my own machine. I will also be able to use this PC for my assignments, so that's also a plus. my budget is 2000-2500$, so everything but the case, fans, PSU and drive will be second hand.

About the CPU:
I am not considering HEDT platforms due to low-bandwith 4-channel memory. For Intel only one CPU has caught my attention, the Xeon w-3175x for 800$. It has a small cache of 82MB, and 6 channel RAM, so unless it turns out to be an absolute beast, it is not my first option.
My budget option is the EPYC 7551p, which I can have for 220$, but will probably underperform in comparison to others. If it doesn't underperfom signifficantly, it is my first candidate.
The only 2 CPU configurations I'm considering are 2x7371 (2x400$) or 2x7351 (2x180$). They would be 32 cores in total, with 16 total RAM channels, which might be good, but the 2x7371 EPYC Naples configuration is as expensive as an EPYC Rome single-socket configuration.
My EPYC Rome options are the following, all single socket: a 7402p (24-core at 2,8 GHz for 800$) and a 7542 (32-core at 2,9 GHz for 1000$).
Which option would be the better bang for the buck?

About RAM:
Is RAM speed worth a 1000$ increase in price? I can get 8x32GB ECC 2Rx4 at 2133MHz for 480$, stepping up to 3200Mhz brings me way past 1400$.

I would get a dual cpu motherboard and components that will work well with the 7542. Buy the appropriate 16 channels of 3200 MT/s memory for your future dual 7542 config. Maybe 8 Gb RDIMMs to keep cost down. However, install the cheap 2x7351 (2x180$) for now. Your total system cost should be less than your budget. While you are setting up your models, the 7351's will be more than adequate. In the mean time, 7542 processors will become cheaper. You may never need the upgrade, but if you do, it will be drop in.

I have estimated the cost for a complete system, using ebay and pcpartpicker and I think I'll have to extend my budget regardless of what I do.

The base configuration for everything except CPU, Motherboard and RAM is the following (I already have a 1TB M.2 SSD):

RTX 3070: 500$
EVGA SuperNOVA P6: 170$
Corsair 4000D: 95$
Be quiet Dark Rock Pro TR4: 90$
WD Blue 4TB HDD: 60$
Noctua NT-H1: 9$
Noctua P12 1700PWM x6 + splitters: 106$
Monitor, Mouse and Keyboard: ~160$

BASE BUILD TOTAL: 1190$


Single socket options:
For these two I would use the Gigabyte MZ31-AR0, which is a bit more expensive than supermicro alternatives (I've heard they skimp out on the VRM's) and comes in at 450$.
For RAM I'll be using an 8x16GB RDIMM kit at 3200 MHz instead of a 16x8GB. It costs 848$. Both procesors have 128MB of L3 cache

With the 24-core Rome option, the 7402p at 2,8 GHz, Coming in at 800$, the total cost is 3288$.

With the 32-core Build, the 7542 at 2,9 GHz, Coming in at 990$, the total cost is 3478$.

Dual socket options:
For these other builds I would use the Gigabyte MZ72-HB0, which I can get new (unlike the MZ31-AR0) at Newegg for 830$.
For RAM I'll be using an 16x8GB RDIMM kit at 3200 MHz to populate all channels of both cpu's, it costs 960$.

My only Rome option, 2x7302 at 3,0 GHz, Coming in at 852$ (2x427$) for dual 16-core processors, the total cost is 3924$. I like this one as it has double the cache of Naples (128MB per core), but I don't like the price. Choosing the 7282 would mean having half the cache and clocking at 2,8 Ghz, for 98$ less.

These next CPU's are all Naples, so first gen Epyc with 64MB of L3 cache per CPU.
2x7451 (2x24 cores) at 2,3GHz for 254$ each, the build costs 3578$.
2x7351 (2x16 cores) at 2,4GHz for 215$ each, the build costs 3500$.
2x7301 (2x16 cores) at 2,2GHz for 165$ each, the build costs 3400$.

What would you do? Maybe I can cut corners with the secondary components also. Depending on how much I'd save. I'd appreciate any feedback

I would pick 2x7301 (2x16 cores) at 2,2GHz for 165$ each, the build costs 3400$.

I would save on graphics card. They are dropping in price right now, so you could start with a very cheap one and get a lot closer to original budget.

Maybe I could save on the GPU, but I need some horsepower for post-processing (4gb of VRAM would be sufficient I think) so I can’t just get a 50$ quadro and call it a day. Furthermore, I’d like to use this workstation to maje the CAD models. I mean, I have a good enough laptop, but I don’t know about having to use two machines for a single job. Any other recommendations regarding case, psu, cooling…

No further recommendations. I like your proposed system and said so in the other thread.

Thank you :) much appreciated.