[MPlanck]

Hello
I'm new with this. In my school we are going to work with the simulation of biomass combustion using CFX and Fluent. Our current mesh is about 10 million cells.

Our budget is between $4,500 and $5,000 USD, but I don't know the impact of the cahche, threads, cores, RAM, GPU on this kind of phisycs.

I don't know if I should go with Epyc processors or Xeon, etc.

About the GPU we want to buy a Quadro P5000 but I don't know if it's "useless" for our applications.

I'd appreciate some advice on the matter.

Thanks.

[flotus1]

How many parallel licenses do you have access to? It's important to know, because if you can only use e.g. 8 cores there is no point in getting a workstation with much more than that.
Also: are you planning on building it yourself from parts or buy a complete workstation off the shelf? This will affect what kind of hardware you get for your budget.
What I can tell you right away is that an "expensive" GPU like a Quadro P5000 won't be of much use. GPU acceleration with this software is only viable when you have to spend excessive amounts of money for the licenses, and thus spending an additional 20-30k on GPUs to get faster solver times with the same amount of licenses is worth it.

[MPlanck]

Hi, thanks for answer.
I have licence for 16 cores. But let me say that the licences wont be a problem.


About your other question, yes. I'm planning to build the workstation myself. Could that be a problem. I want to do it myself beause i think that I can get better compponents with the same budget.

[flotus1]

So 16 core licenses or unlimited cores???
I forgot to ask...Windows or Linux? I am still reluctant to recommend AMD Epyc to Windows users. Allegedly, the windows scheduler has improved since Epyc was released. But honestly, if you want to run Windows just get Xeons or wait for availability of Epyc 2nd gen. With its simpler NUMA topology, Windows should have less issues

Building it yourself is an advantage, not a problem. You get a lot more performance for your money.
If you are running Linux my recommendation would be 1st gen Epyc. Prices for these CPUs came down by a lot, and there is plenty of DDR4-2666 available for reasonable prices. The configuration could look like this, approximate prices in Europe:

Some dual-socket motherboard, probably Supermicro H11DSi. Get the NT version if you need 10 GBit Ethernet onboard - 600€
2x Epyc 7451 - 1800€ for both of them together (don't buy from vendors that have higher prices listed)
16x16GB DDR4-2666 RDIMM dual-ranked - around 1300€
2x Noctua NH-U14s TR4-SP3 - 160€
Phanteks Enthoo Pro or similar case that can hold SSI-EEB motherboards - 100€
Some case fans to replace the rubbish quality pre-installed fans - 80€
Decent quality power supply with at least 600W and 2 8-pin connectors, e.g. Seasonic Focus Plus Platinum 750W - 120€
1TB NVMe-SSD, e.g. Samsung 970 Evo Plus - 200€
Consumer graphics card in the 200€ price range, e.g. Nvidia GTX 1660 or AMD RX 570/580/590
+as much additional storage on SSDs/HDDs as you need.

To put my money where my mouth is: I got my new Epyc 7551 CPUs in the mail yesterday. I had plans to upgrade to 2nd gen, but with no dual-socket motherboards in sight, some hefty price drops on 1st gen CPUs and available+affordable DDR4-2666, I could not resist.
Why AMD Epyc? It beats Intel Xeon in price/performance for these applications. Plenty of cores, cache and most importantly memory bandwidth due to 8 memory channels per CPU.
Using slow-spinning fans with a Supermicro board, you will have to lower the fan warning threshold via IPMI: https://calvin.me/quick-how-to-decre...fan-threshold/

[MPlanck]

We have two of the HPC-pack-license and each one is for 8 parallel processes. That's why I said that the amount of cores could be up to 16.
Maybe I'm just getting it wrong.


On the other hand we're probably going with windows and that is because apparently my teacher have a Windows 10 PRO licence that we can use. Altough I'm not discarding that we go with Linux.


Do you have any advice in that case (windows)?


Also, where did you get two of the Epyc 7451 for 1800? Were used processors?

[flotus1]

Prices/sources: https://geizhals.eu/?cat=cpuamdam4&x...=p#productlist

Ansys HPC packs: as far as I remember -and according to their own information- , each HPC pack increases the number of threads by a factor of 4 when used for 1 simulation.
1 pack: 8 threads
2 packs: 32 threads
3 packs: 128 threads...
The story is different if you split them across 2 simulations. Then you can only use 8 threads for each of them, not 16.

A windows-friendly alternative:
ASUS WS C621E Sage motherboard: 520€
12x16GB DDR4-2666 RDIMM dual-rank: 1000€
2x Xeon Gold 5218: 1360€ each
The rest of the setup can stay the same.

But in all honesty, "we have a Windows license" does not sound like a valid reason to stick with Windows. Linux is free software, and Ansys products are supported on Linux.