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suflaj t1_j0cxviw wrote

Chassis is not a problem, it's the heat.

Generally anything above 2x 3090 will need to be underclocked or in an open case to be under 90°C.

I don't think a 4x 3090 rig is possible without water cooling, since even with riser cables and an open case the cards are going to be fairly close to one another. The cards will need to be underclocked heavily and you will need the best power supply on the market, and you would still risk shutdowns or even hardware failure if 4 cards go into a transient spike at the same time. I would not risk it if you're building 2 rigs anyways, there is little benefit from a 4x and 2x configuration instead of a 3x and 3x configuration.

NVLink probably won't matter much since your CPU will be bottlenecked trying to send 5.2 TB/s of data to your GPUs. But again, there are no benchmarks to show how much, maybe the gains from NVLink will be noticeable.

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twobadkidsin412 t1_j0e2foy wrote

I had a box fan in front of my mining rig with 6 cards. Was hot but worked great.

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suflaj t1_j0e2job wrote

A mining rig has a load significantly different from DL loads. I work with these cards, we have like 10 rigs in the office with dual/triple 3090s, some Tis, I'm well aware of their limits.

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Moist-Bath5827 t1_j0f0w5y wrote

Do you have a recommendation for 3x? At least the mobo and case?

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suflaj t1_j0fszwu wrote

Probably ROG Strix X570-E. Case doesn't matter much as long as it's a full tower, but as for the brand, Fractal usually makes good cases. Specifically, Fractal Torrent is the best all around case IMO, but they're sort of hard to find.

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Outrageous_Room_3167 OP t1_j0ddpsu wrote

>NVLink probably won't matter much since your CPU will be bottlenecked trying to send 5.2 TB/s of data to your GPUs. But again, there are no benchmarks to show how much, maybe the gains from NVLink will be noticeable.

I guess the bigger benefit of the NVLink is the larger memory, but aside from that, I don't think the performance gains are huge from what I've read. My thinking was to build out a chassis with external fans as well to cool everything down.

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suflaj t1_j0de8ja wrote

There is no larger memory. NVLink only increases bandwidth by up to 300 GB/s unless there is a software implementation of memory pooling, which there isn't for any relevant DL framework.

Every week this has to be explained to yet another aspiring system integrator...

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ribeirao t1_j0e5fow wrote

Not op but that’s good to know, so it would only speed the process and not make a big gpu with 24+24 gbs :(

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suflaj t1_j0e646v wrote

You can always make a model parallelized model and have it on any card, not that hard. Your biggest problem is load balancing in that case, but it can be done with a bit of benchmarking and heuristics.

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ribeirao t1_j0e6lkg wrote

thanks for the keyword, I’ll keep this in mind when/if I buy another 3090

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