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April 23, 2021, 11:22 |
Specs for a good workstation
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#1 |
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I am trying to finalise specs for my workstation (Dell Precision 7820), with a view to using 2 HPC packs (so 32 core licence) with FLUENT (standard 4 core licence) and need some advice. I have provided the details below, along with the points on which I need help.
Processor: Dual Xeon Gold 6242R (40C, 3.1GHz base, 4.1GHz Turbo) or Dual 6246R (32C, 3.4GHz base, 4.1GHz Turbo) 6242R has lower base clock speed but more no. of cores, so I would be able to utilise 32 cores with HPC along with 4 cores with standard licence, and still leaving 4 cores for any other tasks (e.g. pre/post processing etc). 6246R has higher clock speed (+0.3GHz) however 32 cores so I can't even utilise all the cores included in HPC and standard licence. While turbo frequency for both is same at 4.1 GHz, according to Dell, at a time turbo mode is only used for 8 min and the clock speeds go back to base level to manage thermal workload, so I am assuming that both processors will largely run at base clock speed. I am inclined to go with 6242R despite its lower clock speed, however am interested in any recommendations Memory: 12X16GB (=192GB) or 12X32GB (=384GB) DDR4 2933 MHz ECC RAM I will be running the simulations of mostly internal flows (single phase and multiphase/multispecies, which could at times be transient) with mesh count upto 15 million elements in FLUENT and wondering whether there is any point in going beyond 192GB RAM. Since this is a workstation, I will be using it while it is running simulations (for pre/post processing or CAD etc). however trying to understand if there is rationale in getting 192GB+ RAM. Also can someone please explain why is it important to populate all memory channels of the processors? Boot drive: 2TB M2 NVMe SSD This will avoid any I/O bottlenecks while running simulations so preferred over SATA SSD. Graphics card: NVIDIA RTX 4000 8GB Suitable for general rendering and animations etc. Not intending to use GPU acceleration as this is fairly low specced card |
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April 23, 2021, 12:49 |
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#2 | |
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Alex
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Quote:
Before going into detail about any of this: Intel has already released their third generation of "scalable" Xeon CPUs: https://www.anandtech.com/show/16594...calable-review If you can, get a workstation with those CPUs. They have been out in the wild for quite some time now, and I see no reason why large OEMs like Dell would not be able to sell workstations with current-gen CPUs by now. |
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April 23, 2021, 13:32 |
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#3 | ||
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Quote:
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https://ark.intel.com/content/www/us...=199353,212457 That said, I am limited to a budget of £10k, and want to utilise 2 HPC packs fully (so 32+4 cores) hence looking at the 40 core processor. We need the machine in next couple of weeks, so if Dell can't manage the third generation chips, we have to contend with 2nd generation. Can you comment on the two processors listed and my dilemma about no. of cores and clock speed etc? Also would appreciate any thoughts on the other aspects of the configuration I have listed. |
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April 24, 2021, 02:43 |
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#4 | |||
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Alex
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About Intels turbo boost and similar technologies: https://en.wikichip.org/wiki/intel/frequency_behavior
Turbo tables for individual CPUs are often hard to come by. Here is one for the Xeon Gold 6242: https://en.wikichip.org/wiki/intel/xeon_gold/6242 I can't find the same info for the refresh variant: https://en.wikichip.org/wiki/intel/xeon_gold/6242r But in general: the higher the TDP rating, the higher the turbo boost table values. Or if you compare two CPUs with similar TDP but different core counts: For the same amount of cores active, they will usually run at similar frequencies. So don't rule out CPUs with high core counts, just because their base frequency is lower. It has to be, in order to fit the TDP envelope when all cores are active. Quote:
What matters here is the power setting in the operating system, on top of any limitation that might come from the bios. E.g. you could disable turbo boost entirely in the bios, or the vendor could do that for you. Which is what I was referring to as "something particularly stupid" tl;dr: the 20-core 6242R is a good choice, despite its lower base clock speed. Picking a CPU with lower core count just for the higher base clock speed is not worth it. Quote:
Filling all memory channels is important, because memory bandwidth matters in parallel CFD. That's the main reason why I brought up 3rd gen scalable CPUs. And you can only get the maximum memory bandwidth by populating each channel with a DIMM. General recommendations for CFD hardware [WIP] In order to squeeze out the last few percent of memory performance, you could try asking Dell to use dual-rank memory modules for that 12x16GB configuration. But that's probably not something you have any control over. Quote:
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April 26, 2021, 11:08 |
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#5 | ||||
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https://www.dell.com/en-uk/work/shop...a579532/memory Quote:
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April 28, 2021, 10:36 |
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#6 | |||
Super Moderator
Alex
Join Date: Jun 2012
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Quote:
Well maybe apart from the amount of free DIMM slots on these machines, please double-check before you attempt something like that. Quote:
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But that explanation you got is just a bunch of nonsense. Large OEMs like DELL, HP etc. get access to these CPUs way before they are released publicly, and they work closely together with the CPU manufacturer. With the explicit goal of having systems ready for sale as close to the official release as possible. For this generation in particular, the CPUs have been available to "special" customers many months before the official launch. The CPUs being launched a short while ago is an excuse, not an explanation. |
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