I built a dual-Epyc 7773X server ! It's FAST... and unstable (pics added)

You can do something like this, with a plate heat exchanger inside, then have a rain barrel outside.
These can exchange about 200k btu/hour.
Just make sure to add an air stone and bubbler to your rain barrel or it will eventually get too hot.

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Hello everyone,

I really couldn’t help but chime in on the discussion about using Epyc CPUs for CFD work we are using Milan here though. As an aerodynamicist who has been using a similar setup for the past three years, I’ve found them to be quite stable in general. We faced the same challenge with those identical coolers as well. Really you want them rotated 90 degrees to exhaust out the back of the case.

I agree with the post about these motherboards being designed for racks with front-to-back flow and coolers that don’t blow in that direction. In my experience, adding more fans and cooling isn’t the ideal solution; sometimes, a simple duct can be more effective. We’ve had success with 3D printing them for this kind of case, but many materials and techniques can work.

From looking at your computer, it seems to me that the high-heat CPU exhausts are blowing over the VRMs. I would suggest ducting the intake air to cool them directly or venting the CPU exhaust out the back and away from the VRMs. Personally, I prefer the latter option. Some fans to mix cold air with the exhaust air as a less-than-ideal solution that might work though I prefer to keep things cooler than that. When we design cooling systems, “hot things hot and cold things cold” is a central philosophy. So just mixing good and bad to make lukewarm isn’t really my favorite.

On a different note, I’m also curious (excited) about what solution you’re working on with that long solve time but fits in such a small amount of memory. I don’t want to pry into confidential information, but I’d love to hear about it if you’re willing to share more.

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The plate heat exchanger is major overkill, but they work extremely well. I used them in industrial medical equipment. You don’t even have to have all the much water flow in the external circuit. City water temp is fine.

I’m doing marine CFD. Incompressible RANS VOF with wall functions. Approx. 10GB RAM per million cells ! On not too large 5 DOF calculations, I need 1 day to simulate 1 sec. of physical time…

A relatively easy way to duct air to a particular spot is to use the lines from:
https://www.loc-line.com/
The 3/4 inch system may work well for you.

I usually pick up some sufficiently temperature rated plastic. If you are in the US, most cities have TAP Plastics, easy enough to cut with scissors and then glue it together with epoxy.

If the exhaust air from the CPU is 80 degrees, blowing over the CPU comes out on the parts you will work very hard to get the temperatures low where a duct could expose them to near ambient air even a modest flow rate is huge.

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