[LukeaUS]

Hi all,

Quick sanity check here! Planning to put together a simulation PC for primarily CFD work (and some FEA), however we only have access to up to 4 cores (sometimes only 2 cores) - so prioritising clockspeed instead of high core + high memory channels.

Occasionally doing RANS sims of ~20+ million elements, hence the high RAM (192 GB), at a minimum I'd be after 128 GB.

Components: On newegg


1. AMD Ryzen 5 7600X Desktop Processor
2. ASUS ROG CROSSHAIR X670E HERO Motherboard
3. 2xCorsair VENGEANCE RGB 96GB (2x48GB) PC5-44800 (5600MHz) DDR5
4. Fractal Design Meshify C Black ATX Case, T/G Side Window, No PSU
5. Gigabyte GeForce RTX 3060 VISION OC 12G R2.0, 12GB
6. NZXT Kraken X73 Liquid CPU Cooler
7. Seasonic Focus GX-850 850W Power Supply
8. Western Digital WD Blue 2TB SSD, 3D NAND WDS200T2B0A

Anyone see any issues here, or anything else you would choose instead? Currently priced at around $4500 (Australian Dollars).

Thanks!

[wkernkamp]

The memory shows " compatibility: Intel 600 Series,Intel 700 Series" on the corsair website.

[flotus1]

Support for 192GB total is slowly trickling in for Intel 13th gen and AMDs Ryzen 7000.
It is worth noting that both CPU lines support a maximum of 128GB according to Intel and AMD. This spec is due to the non-availability of 48GB UDIMMs at launch, but still: choose wisely, and update to the latest bios version.

What does this mean for you?
1) Pick an Intel CPU. The I5-13600k seems to be the obvious choice.
Memory support is usually better for Intel CPUs. And since you will be using bleeding edge technology, this will make things easier.
2) Use a memory kit that comes with 4x48GB. Mixing two "identical" kits with 2 DIMMs each is usually no problem. But for this particular case, I would not take any chances. Corsair seems to be the only supplier at this point: https://geizhals.eu/?cat=ramddr3&sor..._DDR5%7E256_4x
3) As already mentioned: update the bios to the latest version. And be prepared to run the memory slower than advertised.
4) MSI was the first motherboard manufacturer to announce support for 192GB. Either get an MSI board, or check which other manufacturers did the same.

Overall, 4500AUD or almost 3000€ seems like an awful lot of money, for a moderate amount of computer. Maybe pick components individually, instead of using an online configurator.
The motherboard in particular is unnecessarily expensive.

[LukeaUS]

Thanks for your input!

Yeah I'm aware of that "max of 128 GB" note, however had found mention online of people successfully running more and it was, like you mentioned, just due to the availability of higher UDIMMs at launch.

As for the Intel I5-13600k vs. the AMD Ryzen 5 7600X, would there not be an immediate 25-35% slowdown here purely due to clockspeed? Or is real-life sufficiently different to the advertised specs?

Noted on the motherboard, I simply used newegg to make sure the components were compatible to each other, and chose 'relatively' well reviewed components - I'm too far gone from having a good understanding of the hardware many years ago and just decided to solve my ignorance with some pragmatism and money! I had a quick look, but none of the MSI offerings 'supported' 192 GB RAM, I'm assuming this is likely for the same reasons most of the CPUs also stop at 128, and that they would in reality support higher?

Thanks again.

[flotus1]

Not sure where you got 25-35% difference in core clock speed for the 7600x vs 13600k.
Out of the box, they have single-core turbo frequencies of 5.3GHz and 5.1GHz respectively. And in terms of actual single-core performance, they are pretty much identical.
Base clock speed doesn't matter here, and neither does the frequency of the E-cores on the 13600k. They don't run at base clock with sufficient cooling, and the E-cores should not be used by the solver.

And chances are, you will need overall slower settings on the memory to get it running stable on the Ryzen CPU. 4 cores is already in the realm of bandwidth limitation with these CPUs. And even for 2 cores, slower memory latency will make a difference.

[LukeaUS]

That was just based off the base clock speeds.

Didn't realise the benchmarking sites broke it down into single/dual etc core performance: https://cpu.userbenchmark.com/Compar...00X/4134vs4130

Great - appreciate the correction! What is your thoughts on memory if we proceed with the i5-13600K, DDR5 much of an improvement over DDR4? It seems the absolute latency of the DDR5 is 'generally' worse than good DDR4, despite the higher frequency.

Likewise, any feedback on GPU?

[flotus1]

Since you want more than 128GB of RAM on this platform, DDR4 is out of the picture anyway.
But in general, DDR5 is a nice performance boost for CFD applications. The huge increase in bandwidth more than makes up for slightly higher latency for our needs.

GPU...see section 3 here: General recommendations for CFD hardware [WIP]
tl;dr: An RTX 3060 is not a bad choice here, since it has a fairly high amount of video memory. And prices should be more reasonable now.

Side-note: Userbenchmark gave me a good chuckle. Whoever manages this site is delightfully off the rails, with their conspiracy theory about AMD paying reviewers and shills on social media. Just an excerpt from your link, but they have been doing this for years now, and it seems to be getting worse every time I look.

Within minutes of the first, pre-release, 7000 series userbenchmark results, AMD’s marketers broadcast a 20% win over the 12900K via thousands of anonymous twitter, reddit, forum and youtube accounts. Buying new AMD products is like buying used cars: it takes time, experience and a taste for sales hype. It’s difficult for consumers to make rational choices while AMD completely dominates “sponsored news” and social media channels. Ten years ago, when AMD was the underdog, this type of marketing was understandable. Today, with a capitalization of $150 Billion USD, it’s disrespectful to AMD's own users. Even with Intel's marketing department asleep at the wheel, Ryzen will quickly end up in the same state as Radeon. Following a series of overhyped releases, consumers have little interest in the Radeon brand.