You get occasional accounts of 3090 home-superscalers whereas they would put up eight, ten, fourteen cards. I normally attribute this to obsessive-compulsive behaviour. What kind of motherboard you ended up using and what's the bi-directional bandwidth you're seeing? Something tells me you're not using EPYC 9005's with up to 256x PCIe 5.0 lanes per socket or something... Also: I find it hard to believe the "performance" claims, when your rig is pulling 3 kW from the wall (assuming undervolting at 200W per card?) The electricity costs alone would surely make this intractable, i.e. the same as running six washing machines all at once.

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jacquesm a day ago | parent [-]

I love your skepsis of what I consider to be a fairly normal project, this is not to brag, simply to document.

And I'm way above 3 kW, more likely 5000 to 5500 with the GPUs running as high as I'll let them, or thereabouts, but I only have one power meter and it maxes out at 2500 watts or so. This is using two Xeons in a very high end but slightly older motherboard. When it runs the space that it is in becomes hot enough that even in the winter I have to use forced air from outside otherwise it will die.

As for electricity costs, I have 50 solar panels and on a good day they more than offset the electricity use, at 2 pm (solar noon here) I'd still be pushing 8 KW extra back into the grid. This obviously does not work out so favorably in the winter.

Building a system like this isn't very hard, it is just a lot of money for a private individual but I can afford it, I think this build is a bit under $10K, so a fraction of what you'd pay for a commercial solution but obviously far less polished and still less performant. But it is a lot of bang for the buck and I'd much rather have this rig at $10K than the first commercial solution available at a multiple of this.

I wrote a bit about power efficiency in the run-up to this build when I only had two GPUs to play with:

https://jacquesmattheij.com/llama-energy-efficiency/

My main issue with the system is that it is physically fragile, I can't transport it at all, you basically have to take it apart and then move the parts and re-assemble it on the other side. It's just too heavy and the power distribution is messy so you end up with a lot of loose wires and power supplies. I could make a complete enclosure for everything but this machine is not running permanently and when I need the space for other things I just take it apart, store the GPUs in their original boxes until the next home-run AI project. Putting it all together is about 2 hours of work. We call it Frankie, on account of how it looks.

edit: one more note, the noise it makes is absolutely incredible and I would not recommend running something like this in your house unless you are (1) crazy or (2) have a separate garage where you can install it.

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tucnak 12 hours ago | parent [-]

Thanks for replying, and your power story does make more sense all things considering. I'm no stranger to homelabbing, in fact just now I'm running both IBM POWER9 system (really power-hungry) as well as AMD 8004, both watercooled now while trying to bring the noise down. The whole rack, along with 100G switches and NIC/FPGA's, is certainly keeping us warm in the winter! And it's only dissipating up to 1.6 kW (mostly, thanks to ridiculous efficiency of 8434PN CPU which is like 48 cores at 150W or sommat)

I cannot imagine dissipating 5 kW at home!

	▲	jacquesm 3 hours ago \| parent [-]
		I stick the system in my garage when it is working... I very enthusiastically put it together on the first iteration (with only 8 GPUs) in the living room while the rest of the family was holidaying but that very quickly turned out to be mistake. It has a whole pile of high speed fans mounted in the front and the noise was roughly comparable to sitting in a jet about to take off. One problem that move caused was that I didn't have a link to the home network in the garage and the files that go to and from that box are pretty large so in the end I strung a UTP cable through a crazy path of little holes everywhere until it reaches the switch in the hallway cupboard. The devil is always in the details... Running a POWER9 in the house is worthy of a blog post :) As for Frankie: I fear his days are numbered, I've already been eying more powerful solutions and for the next batch of AI work (most likely large scale video processing and model training) we will probably put something better together, otherwise it will simply take too long. I almost bought a second hand NVidia fully populated AI workstation but the seller was more than a little bit shady and kept changing the story about how they got it and what they wanted for it. In the end I abandoned that because I didn't feel like being used as a fence for what was looking more and more like stolen property. But buying something like that new is out of the ballpark for me, at 20 to 30% of list I might do it assuming the warranty transfers and that's not a complete fantasy, there are enough research projects that have this kind of gear and sell it off when the project ends. People joke I don't have a house but a series of connected workshops and that's not that far off the mark :)