[shock77]

Hi everyone,


I am thinking about building a low budget workstation (1000€-1200€) and would like some recommendations on my build and my thoughts.
I use OpenFOAM and mostly the solver rhoCentralFoam. The OS is Linux (Ubuntu). The number of cells is usually around 1 - 5 million.


I am thinking of purchasing these parts and build it myself:

CPU: Ryzen 9 5900x 12x3.7 GHz up to 4.8 GHz (390 €)
GPU: Saphhire Radeon RX6600 8 GB (320€)
RAM: 2x 16GB G.Skill Aegis DDR4-3200 DIMM CL16 Dual Kit (100€)
MB: MSI B550-A Pro AMD B550 So.AM4 Dual Channel DDR4 ATX (120€)
Cooler: Scythe FUMA 2 Rev. B, CPU-Kühler - 2x120mm (60€)
Power Supply: 750 Watt ADATA XPG Core Reactor Modular 80+ Gold


with an aditional casing I will be around 1150 €.


I have spent a lot of thoughts about the CPU. There is also the 5950x (16 cores) and the 5800x (8 Cores), which are 100€ more or 100€ less than the 5900x. Since these CPUs are all dual channel, I think the bottle neck is the band width and therefore the 5950x is not worth it. I still think the 5900x is worth the money compared to the 5800x, since the L3 cache is doubled. This is more or less confirmed here: https://openbenchmarking.org/test/pt...f51edd#metrics
The 5950x and 5900x CPU perform more or less equally, while the 5800x is clearly outperformed.


What do you think about this build? Is it worth the money? Should I rather wait for the new generation? I think it will be massivly faster, on the other hand good DDR5 memory is needed, which is way more expensive.

[trans(sonic)_pride]

If you want it strictly for CFD maybe you could get a deal on some older dual xeon based combos on aliexpress, which could potentially be better (specially xeon v4's on x99). Look into it. Apart from that, this is pretty much the best you can get for the money, I'd only recommend to add a 5-pack of arctic p12 fans to your build. They're very cheap (the pack is like 32$) and perform very well and quietly. The more fans you have the quieter your build is.

[shock77]

Thanks for your recommendations!


Indeed, there are some really cheap CPUs on aliexpress. I have never bought anything there, how reliable is the support and is there warranty?


The fans are for the case, right? I willl add some extra fans, thanks!

[wkernkamp]

Originally Posted by shock77

Hi everyone,

CPU: Ryzen 9 5900x 12x3.7 GHz up to 4.8 GHz (390 €)

I have spent a lot of thoughts about the CPU. There is also the 5950x (16 cores) and the 5800x (8 Cores), which are 100€ more or 100€ less than the 5900x. Since these CPUs are all dual channel, I think the bottle neck is the band width and therefore the 5950x is not worth it. I still think the 5900x is worth the money compared to the 5800x, since the L3 cache is doubled. This is more or less confirmed here: https://openbenchmarking.org/test/pt...f51edd#metrics
The 5950x and 5900x CPU perform more or less equally, while the 5800x is clearly outperformed.

You should also consider the 5800X3D. Very decent results found 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.

[shock77]

Oh yes, I am also considering the 5800X3D. On https://openbenchmarking.org/test/pt...1235fa#metrics he is also slightly better than the 5900x. Also the power consumption is lower, which may outweight the higher price (90€ higher).


However I think I need high clockspeeds, because the bottleneck in some simulations is actually the timestep for supersonic calculations. Even and especially for small meshes. The 5900x has 7% higher clockspeeds (4.8 Ghz to 4.5 GHZ). Also I think AMD GPUs profit from higher core counts for rendering.


But yes, its really a tough choice.

[trans(sonic)_pride]

Originally Posted by shock77

Indeed, there are some really cheap CPUs on aliexpress. I have never bought anything there, how reliable is the support and is there warranty?

It depends on the seller. It is a bit of a risk, but usually there aren't any problems with reputable sellers. Look at this tread and see if any of the v4 xeons are good price-to-performance. BTW, yes, the fans are for the case and they're the best bang for the buck according to this video

[shock77]

There are some very interesting offers like a INTEL XEON E5 2680 V4 for 100 €. I am pretty sure two of those will clearly outperform a 5900x for large mesh sizes for subsonic cases, but I still think I will stick to higher CPU clockspeeds for supersonic simulations.


Thanks also for this nice video!

[trans(sonic)_pride]

If you think the 5900X or 5800X3D will be better suited for your application go for it, they’re surely the best desktop processors for cfd ever released excluding hedt. Glad you found the video useful.

[shock77]

I think I will go for one of those. Thanks again for your input and kind advice!

[nmc1988]

Originally Posted by shock77

I think I will go for one of those. Thanks again for your input and kind advice!

You may consider i5-12600 with ddr5 6000mhz like this benchmark
It is faster than 5800x3D


OpenFOAM benchmarks on various hardware

In total Dkr 7.533 which is € 1005 or $ 1147 (prices are excl V.A.T)
The components are:

Intel i5-12600 (Dkr 1599,20)
Kingston Fury Beast 2x16 GB 6000 MHz (Dkr 2636,80)
Asus TUF Gaming B660M-plus wifi (Dkr 1247,20)
Samsung 970 EVO plus 1TB (Dkr 709,60)
Noctua cpu (NH-U9B SE2) and cabinet coolers (Dkr 525,60)
Seasonic Focus GX550 (Dkr 479,20)
Fractal Design Core 1100 (Dkr 335,19

[shock77]

Thanks for your suggestion!


The result look decent but I cant find a direkt comparison of both CPUs. Could you show me where to find it?


Also the system is around 1200 € with VAT and without a GPU, which is needed for paraview and blender. So in total it would be around 1500-1600 €, which is a third more expensive than my setup. Good DDR5 Ram is very expensive atm, so I think I would rather wait and use this cheap system I suggested for now.

[shock77]

Judging by this site and the motoBike OpenFOAM case, the i5-12600K is slower than the 5900x and the 5800x3D: https://openbenchmarking.org/test/pt...1235fa#metrics


It may depend on OS, used RAM and so on.

[flotus1]

Try not to rely on that site too much.
The numbers posted there are very unreliable. Both from a common sense perspective, and when comparing against real benchmarks.

[shock77]

I am not familiar with high-end CPUs and also I am not an expert on low-end CPUs, but the results did not arouse any suspicion in me. Why is the site not trustworthy?

[flotus1]

We could not determine what exactly causes the discrepancies. Part of that will be that no information on memory is recorded. But that can't be the only issue. I have seen news sites reporting benchmarks with systems that could not possibly have enough memory to run the benchmark at all.
All we could find out is this: the results are mostly useless.

[CFDfan]

Originally Posted by trans(sonic)_pride

It depends on the seller. It is a bit of a risk, but usually there aren't any problems with reputable sellers. Look at this tread and see if any of the v4 xeons are good price-to-performance. BTW, yes, the fans are for the case and they're the best bang for the buck according to this video

I bought, over the years, 3 xeons v4 for x99 MB and am quite happy with them. Yes there is a risk when dealing with Aliexpress and the most important factor of reducing the risk is to buy from reputable supoplier with alot of sales. The reputation is measured there in % and it should be above 98%, though you can't trust much Chinese suppliers about that. Product support and returns are practically non-existent. Once you pay for the item they stop answering your messages (if any). Anyway, I've been lucky

[shock77]

Originally Posted by flotus1

We could not determine what exactly causes the discrepancies. Part of that will be that no information on memory is recorded. But that can't be the only issue. I have seen news sites reporting benchmarks with systems that could not possibly have enough memory to run the benchmark at all.
All we could find out is this: the results are mostly useless.

Yeah the cases seem hard to reproduce due to lack of information, but I hoped that it will give me a good overview of different CPUs. I think I will run the benchmark test you suggested in your thread and post it there, once the system is here, I have already bought it.

I bought, over the years, 3 xeons v4 for x99 MB and am quite happy with them. Yes there is a risk when dealing with Aliexpress and the most important factor of reducing the risk is to buy from reputable supoplier with alot of sales. The reputation is measured there in % and it should be above 98%, though you can't trust much Chinese suppliers about that. Product support and returns are practically non-existent. Once you pay for the item they stop answering your messages (if any). Anyway, I've been lucky

Since I need this computer also for common stuff, I dont want to risk it and end up with half of a computer with some parts working and some dont. For a workstation only in a few years I think thats actually a great Idea and might be worth the risk. I will definitly keep that in mind, thank you! Since my budget is limited, I cannot afford to risk it atm.

[CFDfan]

Originally Posted by shock77

Yeah the cases seem hard to reproduce due to lack of information, but I hoped that it will give me a good overview of different CPUs. I think I will run the benchmark test you suggested in your thread and post it there, once the system is here, I have already bought it.



Since I need this computer also for common stuff, I dont want to risk it and end up with half of a computer with some parts working and some dont. For a workstation only in a few years I think thats actually a great Idea and might be worth the risk. I will definitly keep that in mind, thank you! Since my budget is limited, I cannot afford to risk it atm.

Of course, you do what is needed.
P.S. I found the Aliexpress stores I bought my Xeons v4 from: PC Technology and RE Store (in case you need this information later on)

[shock77]

Thank you very much for the name! If I am going to buy CPUs from aliexpress, I will definitly remember this thread and look up the name.