[Laerte]

Hi everyone !

I am starting a phd position in CFD and I have to choose a workstation for my work. My budget is 2500 euros and I have to buy on the dell website because of an agreement with the funding of the lab. I have read a lot of very interesting posts on this forum on this subject and sadly I cannot order most of the hardware that you guys advice (like the AMD Epyc, or the Nvidia GTX) as they do not appear on the website.

The workstation will be based on debian and most of the work will be done in openfoam (or other C++, fortran cfd codes)

For now I have :

. 64Go 2666MHz DDR4 (4x16Go)
. Nvidia Geforce RTX2060 (6Go, 2x DP + 1x HDMI + 1x DVI)
. Intel Core i99900 (8 curs, 3.14.9Ghz Turbo, 16 Mo cache)
. SSD 1To M.2 PCIe NVMe Classe 40


What do you think ? I am mostly concerned about the GPU, will it be enough to have good post proc with paraview ?

Thanks in advance !

[Habib-CFD]

Think about these items if available:

. 64GB 2933 to 3200MHz DDR4 (4x16Go)
. Intel Core i9-9820X or Core i9-10900X (10 cores)
. SSD 256G or 500G M.2 PCIe NVMe

The mentioned Geforce RTX2060 is quite strong for your purpose. The 1Tb NVMe is very expensive and you don't need it. There are very low-cost SATA SSD options as beside the bootable NVMe. You can easily add after receiving your case, just discuss it with your advisor.

[Laerte]

Thanks a lot for your answer !


Ok great for the Graphic card, the post processing will be a big part of this computer use so I would like to be able to run fluently results on paraview.


Sadly, this is the only SSD available in the options, and I do believe that I could be way more efficient with a SSD.

[Noco]

Your specification has a lot of bottle necks for CFD tasks. The main criteria for CFD are:

1. CPU memory channels amount (at least 4, better 8 - that is why even old epyc and xeon are much better, then modern i9900 or analogue with only 2 memory channels) + RAM double rank 2333 min, better 3600 or higher

2. Amount of cores (at least 8, optimum 16)

3. Motherboard with 2x8 pins for power or more, at least gold power supply 650 W+ , or CPU cores will not reach maximum GHz (do not trust 65-85 W on intel ark, check youtube to understand actual consumed power for CPU you choose)

4. SSD can be changed for 4-6 HDD in RAID 0 - same speed, but bigger volume for big tasks

5. GPU is not important for CFD. But if you need to have more universal build and run fast Solid, Katia - better to buy Quadro 4000 6000 or AMD analogue.

If dell and 2500 EUR, I will think about this:
https://www.dell.com/en-us/work/shop...oweredge-r6515

1U epyc 16 cores or
2U epyc 16 cores

for each CPU:
8x8 dual rank 2666 or
8x16 dual rank 3666

[flotus1]

I try not to nitpick too much, but I have some objections to the points you made.

Motherboard with 2x8 pins for power or more, at least gold power supply 650 W+ , or CPU cores will not reach maximum GHz

If a PSU can not deliver enough power, it does not result in lower clock speed for desktop PCs. Instead, the PSU shuts off (if it has working protection) or fails catastrophically.
The amount of connectors you need is determined by the hardware. If the motherboard does not even have a second 8-pin, then you don't need it. Even single-socket boards that have this connector run fine without it being connected, at least within official specs.

SSD can be changed for 4-6 HDD in RAID 0 - same speed, but bigger volume for big tasks

A RAID0 of several spinning disks is no replacement for an SSD. It can reach similar sequential throughput, but this is where the similarities end.
SSDs have much lower latency and much higher throughput for smaller chunks of data. 6 HDDs will draw much more power and produce much more noise than an SSD, and take up more space. And a RAID0 with this many disks is prone to failure. If one disk fails, the data is gone.

If dell and 2500 EUR, I will think about this:
https://www.dell.com/en-us/work/shop...oweredge-r6515

This is a server blade, not a workstation

1U epyc 16 cores or
2U epyc 16 cores

for each CPU:
8x8 dual rank 2666 or
8x16 dual rank 3666

There is no compatible memory for Epyc rated at DDR4-3666. And Epyc second gen CPUs are limited to DDR4-3200 maximum. Which is what you should use with 2nd gen Epyc, not DDR4-2666.

[Noco]

Originally Posted by flotus1

I try not to nitpick too much, but I have some objections to the points you made.


If a PSU can not deliver enough power, it does not result in lower clock speed for desktop PCs. Instead, the PSU shuts off (if it has working protection) or fails catastrophically.
The amount of connectors you need is determined by the hardware. If the motherboard does not even have a second 8-pin, then you don't need it. Even single-socket boards that have this connector run fine without it being connected, at least within official specs.


A RAID0 of several spinning disks is no replacement for an SSD. It can reach similar sequential throughput, but this is where the similarities end.
SSDs have much lower latency and much higher throughput for smaller chunks of data. 6 HDDs will draw much more power and produce much more noise than an SSD, and take up more space. And a RAID0 with this many disks is prone to failure. If one disk fails, the data is gone.


This is a server blade, not a workstation


There is no compatible memory for Epyc rated at DDR4-3666. And Epyc second gen CPUs are limited to DDR4-3200 maximum. Which is what you should use with 2nd gen Epyc, not DDR4-2666.

Generally I agree.

I have 120 hours+ calculation duration. I have bad experience with 8 pin motherboards, 8+8 are much more stable, 8+4 at least. Even change power supply to bequite 1200. Before I have errors with CPU, relative to power.

RAID0 is not stable in theory, but I use it because I want to have all data for all calculated points - and it is another 100-120 Gb every week. I use RAID0 4 HDD it for 3 years+, no problems. Main disk is 512 Gb SSD.

I have 1st Gen. Misunderstanding.

[iamrahul]

hi
can you suggest dual rank modules to run at 3600 in xmp

[flotus1]

All memory modules advertised as DDR4-3600 will run at that transfer rate... on some platforms.
What matters is which motherboard you are using, which CPU, and how many of these modules you intend to use.

[iamrahul]

Originally Posted by flotus1

All memory modules advertised as DDR4-3600 will run at that transfer rate... on some platforms.
What matters is which motherboard you are using, which CPU, and how many of these modules you intend to use.

hi
thank you for dropping in:


9980xe
Strix-E rev II
16gb *4 modules


Thank you

[flotus1]

To start with, we can take a look at the memory QVL of that board: https://www.asus.com/de/Motherboards.../HelpDesk_QVL/
Note that these lists are by no means exhaustive, or exclusive. Meaning that just because some memory is not on it, does not indicate that it won't run.
Memory QVLs are put together when a board is launched. The manufacturer tests a small portion of the DIMMs available at that time. Which means that the list is not complete at launch. And it is usually not updated when new DIMMs hit the market. New bios versions usually increase memory compatibility.
Long story short: We can see one dual-rank kit rated for DDR4-4000 with 4 DIMMs populated. And a few single-rank kits rated at the same speed, with 8 DIMMs populated. So we are off to a good start, even if there is no 4x dual rank kit rated at exactly DDR4-3600.

Our next stop: https://geizhals.eu/?cat=ramddr3&xf=...=r#productlist
Pretty much all 16GB UDIMMs are still dual-rank. Very few memory brands list this detail in their product specifications, so we will just go with 16GB DIMMs. If you want absolute certainty, use 32GB UDIMMs.
Since we found no exact match on the memory QVL, I would just buy the cheapest 4x16GB Kit available. Be careful with the height of these GSkill DIMMs, they interfere with some air coolers.

If loading the XMP profile should not work out of the box, be sure to update the motherboard bios to the latest version. If it still doesn't work, increase uncore offset voltage a bit (start with 100mV and increase further if still unstable). That usually does the trick on X299.