[Uffe]

Hello,
I need hardware recommendation for Autodesk CFD (currently 2023)
Current workstation has an i7-7820X CPU and it's pretty slow.
So I'm thinking of build a new computer with more performance to run CFD but also be able to use it for CAD (Inventor)

To quote Autodesks recommendations:
CPU Recommendations:
CPU clock speed has a significant influence on solver speed.
The faster the clock speed the shorter the solve times.
Important: CFD solver uses CPUs (or cores) in a 2^n order.
The 2^n comment means that only these core counts are used 2, 4, 8, 16, 32, so on ...
If a machine has 2x8-core CPUs (that is, 16 cores) the solver uses all of them. If it has 20 cores, the solver uses 16.
Example: It’s better to have 16 x 3.0-GHz cores than 20 x 2.6 GHz or 2.8-GHz cores.
Link for Autodesk CFD hardware recommendations
Otherwise they don't give recommendations regarding bandwith and L3 cache size.

Which software do you intend to use:
Autodesk CFD 2023

Are you limited by license constraints:
No

What type of simulations do you want to run? And what's the maximum cell count?
Airflow in ducts an similar products. Up to approx 10M elements

If there is a budget, how high is it:
Approx 8000 euro

What kind of setting are you in:
Design Engineer

Where can you source your new computer:
Thinking of buying parts and assemble by my self.

Which part of the world are you from:
Sweden

Anything else that people should know to help you better:
If I go after Autodesks recommendations I think I would choose a Epyc 9174F, that has base clock 4,1 GHz and L3 256MB.
Fill up all Ram slots (8,12 or 16 depending on motherboard config) with recommended 16GB memory.
Regarding the Epyc 9174F, what's the suffix F stands for?
If I have a MB with 8 Ram slots, will it be unbalanced when the CPU has 12 memory channels?

[flotus1]

I don't have any experience with that software. So take my ramblings as what they are: just my 2 cents, based on experience with other CFD solvers.

What sticks out from their hardware recommendations:

In Autodesk CFD, there is roughly a 20% speed-up when moving from 4 to 8 cores. An approximate 10% speed up when moving from 8 to 16 cores. The speed improvement is smaller when moving from 16 to 32.

They either tested in an extremely memory-bound scenario, or their solver has very significant serial sections. I.e. Amdahl's law. We can't know for certain.
But I would probably pick hardware with a focus of maximum per-core performance, and low inter-core latency.

Regarding the Epyc 9174F, what's the suffix F stands for?

F means frequency optimized. I.e. higher clock speeds than the normal Epyc CPUs. Which is what we want here.

If I have a MB with 8 Ram slots, will it be unbalanced when the CPU has 12 memory channels?

That certainly would not be optimal. I would strongly suggest to pair this CPU with a motherboard with 12 DIMM slots. Or 24 if there really are no alternatives.

With how Autodesk describes their solver scaling, this might be one of the rare cases where a Xeon W5-3435X is the better choice. It is no longer a monolithic die, but latencies should still be lower than on AMDs latest Epyc CPUs. And the 8 memory channels are still plenty for only 16 cores.
You can even pick "overclocked" memory for these CPUs.
https://geizhals.eu/asrock-w790-ws-a...loc=pl&hloc=uk
https://geizhals.eu/kingston-fury-re...loc=pl&hloc=uk
Another upside is that there are actual workstation motherboards for these CPUs. With all the bells and whistles like USB-ports
With AMD Epyc, you would have to make do with a server board. Which will work, but it has annoyed me for years that nobody makes workstation boards for AMD Epyc CPUs.

[Uffe]

Originally Posted by flotus1

With how Autodesk describes their solver scaling, this might be one of the rare cases where a Xeon W5-3435X is the better choice. It is no longer a monolithic die, but latencies should still be lower than on AMDs latest Epyc CPUs. And the 8 memory channels are still plenty for only 16 cores.
You can even pick "overclocked" memory for these CPUs.
https://geizhals.eu/asrock-w790-ws-a...loc=pl&hloc=uk
https://geizhals.eu/kingston-fury-re...loc=pl&hloc=uk
Another upside is that there are actual workstation motherboards for these CPUs. With all the bells and whistles like USB-ports
With AMD Epyc, you would have to make do with a server board. Which will work, but it has annoyed me for years that nobody makes workstation boards for AMD Epyc CPUs.

@flotus1 thanks for your thoughts and advise.
Seems to be a solid build, not so expensive too.
Also with a workstation motherboard the installation of OS would be easier for me.
I've been looking of another build with CPU: AMD ryzen Pro 7975WX (32c, 4 GHZ, L3 128 MB, DDR 5 5200)
Motherboard: Asrock WRX90 WS EVO

More cores (might not be necessary?) higher L3 and faster clockspeed.
Don't know about the core latencies on this vs Xeon w5-3435X (was hard to find data on that)
What would you think about this build?

I was looking for AMD ryzen Pro 7955WX (16c, 4,5 GHz) but couldn't find it for sale OEM.

BR/Uffe