[gumersindu]

Hi all,

I'm an aerospace engineer currently on my way to start my small business in CFD. To try different setups and run tests, I want to buy/build a workstation since my current laptop is incapable . The use of this workstation will be performance oriented for CFD computations, mainly with OpenFOAM. However, I have a limited budget of around 800-1000€.

I've read some threads about the recommendations on this topic and I can't really decide whether I should assemble my workstation from scratch with used components or just buy a used workstation. I've read some suggestions on buying old HP Z840. Is it even worth it to assemble a workstation under a low budget? What is the current consensus on this?

I also have a question on the techincal side, I understand that for CFD computations I should focus on total memory bandwidth only or also high L3 cache? I understand that in terms of GPU a minimum is enough.

Here I leave my needs:

1. Which software do you intend to use?
OpenFOAM and my own codes

2. Are you limited by license constraints? I.e. does your software license only allow you to run on N threads?
No

3. What type of simulations do you want to run? And what's the maximum cell count?
Mainly RANS with a maximum cell count of around 50 milion

4. If there is a budget, how high is it?
800-1000€

5. What kind of setting are you in? Hobbyist? Student? Academic research? Engineer?
Engineer and some development

6. Where can you source your new computer? Buying a complete package from a large OEM? Assemble it yourself from parts? Are used parts an option?
Assembling is an option but also OEM, depending on offers

7. Which part of the world are you from?
Spain

If someone could guide me a little bit on this topic I would kindly appreaciate it

Thanks in advance

[gumersindu]

Hi all again,

After some more research I think it is worth it to try to build a workstation with dual AMD EPYC 7501 cpu. Although the price might increase, it is way better than any used workstations I could find on the market. Is it a good idea to go for AMD EPYC?

When it comes to the motherboard I'm a bit lost, could anyone help me on that?

Also, if I only want to do some light post-processing, which cheap graphics card would you recommend?

Thanks again

[andy_]

I recently had a brief look at replacing my £3k workstation with something similar using current technology but was disappointed by the state of the market. Current technology seems to have increased in price enormously since covid but is now reducing in price due to low levels of sales but is still perhaps twice the price one might have expected without covid. If one significantly weights value for money current technology seems to be a non-starter. Pre-covid technology was initially "normally" priced and, although it hasn't fallen as would normally be expected, it hasn't risen much and offers significantly better value for money compared to current technology. Given the high price of new hardware my conclusion was the best value for money for a £3k workstation would likely be to buy a 5 year old "£3k CFD workstation" for £600-800 and wait for the new prices to continue correcting themselves.

Of course there is less life left in a second hand workstation and there is perhaps a 3-4 fold increase in performance available new relative to my current workstation for a bit over £3k using parts current when covid hit which are sourced from different places and the workstation assembled and commissioned oneself. This isn't strictly an apples-to-apples comparison because the old machine was bought complete and tested.

Second hand dual Xeon workstation or new dual EPYC 7000 was where I ended up but you are going to need over 3 times your budget for the latter.

[gumersindu]

HI everyone,

Thanks for the replies!

Originally Posted by andy_

I recently had a brief look at replacing my £3k workstation with something similar using current technology but was disappointed by the state of the market. Current technology seems to have increased in price enormously since covid but is now reducing in price due to low levels of sales but is still perhaps twice the price one might have expected without covid. If one significantly weights value for money current technology seems to be a non-starter. Pre-covid technology was initially "normally" priced and, although it hasn't fallen as would normally be expected, it hasn't risen much and offers significantly better value for money compared to current technology. Given the high price of new hardware my conclusion was the best value for money for a £3k workstation would likely be to buy a 5 year old "£3k CFD workstation" for £600-800 and wait for the new prices to continue correcting themselves.

Of course there is less life left in a second hand workstation and there is perhaps a 3-4 fold increase in performance available new relative to my current workstation for a bit over £3k using parts current when covid hit which are sourced from different places and the workstation assembled and commissioned oneself. This isn't strictly an apples-to-apples comparison because the old machine was bought complete and tested.

Second hand dual Xeon workstation or new dual EPYC 7000 was where I ended up but you are going to need over 3 times your budget for the latter.

Indeed, I'm afraid that I need to increase my budget if I want to use AMD Epyc CPU at all. However, do you think it is worth it?

Originally Posted by BlazeKnightR

I would recommend considering cooling systems for the CPUs

Yes, I forgot to mention that obsiously

Do you know of anyone that has build a server with AMD Epyc 7000 series CPU that I could take as a guideline maybe?

Thanks in advance!

[andy_]

Originally Posted by gumersindu

Indeed, I'm afraid that I need to increase my budget if I want to use AMD Epyc CPU at all. However, do you think it is worth it?

That will depend on your circumstances. In my case I settled on a cheap secondhand dual Xeon and deferring the full purchase while prices continue correcting themselves after covid (assuming they will), another poster opted for secondhand EPYC processors with the rest new.

[gumersindu]

Well I finally decided to go for a secondhand dual Xeon with 2xE5-2690-v4 processors, 8x16GB DDR4 ECC RAM, NVIDIA QUADRO M2000 and 1TB HDD hard drive (probably will change to M2 nvme with a PCIe adapter). Thanks all for the help! I'll benchmark this configuration also and post it in the other thread .

Tell me if you think something must be changed that could bottleneck the performance. Btw, does anoyone know if using a HDD hard drive will impact the computation times?

Best

[CFDfan]

Originally Posted by gumersindu

Well I finally decided to go for a secondhand dual Xeon with 2xE5-2690-v4 processors, 8x16GB DDR4 ECC RAM, NVIDIA QUADRO M2000 and 1TB HDD hard drive (probably will change to M2 nvme with a PCIe adapter). Thanks all for the help! I'll benchmark this configuration also and post it in the other thread .

Tell me if you think something must be changed that could bottleneck the performance. Btw, does anoyone know if using a HDD hard drive will impact the computation times?

Best

the HDD should be replaced with m2 nvme for sure