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Comment by knicholes | Hacker News Reader

I have pretty much the same setup but just 4 3080s in one machine. If you go to rent something from vast.ai, you can see the hardware specs of the most performant machines. I just copied those and pieced together the rest. Learning about PCIe versions and ports was very interesting, as I thought I could use another motherboard for a similar purpose, but just because there are four PCIe 3 slots, it doesn't mean they're all usable at 16x AT THE SAME TIME!

I bought 21 R12 Aurora Alienwares and turned a side-office in my garage into a hot-ass crypto farm with two swamp coolers, four 20A circuits, a 15A circuit, and a bunch of surge protectors. I was always afraid to move something in fear that I'd overload a circuit due to the effort in calculating which power supply was powering which machine(s).

I gave away the 3080s to friends and family and kept the 6 3090s.

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I have a dumb question - what do you do with it? And why is it better to have your own hardware for it?

Will you ever see positive return on investment from building this or is it feeding the nerd chute?

Oh yeah, some days I was making $600-800 profit a day! But most days it was ~$100-$200/day. The problem was "the merge" to Ethereum 2 was soon approaching, but was luckily delayed 1.5 years, so I was able to pull ~$80k profit during that time. It was awesome. But now I have a couple holes in my garage office with big fans installed (one on the bottom for intake and one on the top for exhaust, essentially turning that room into a big computer tower).

> what do you do with it?

>> crypto

QuantFinance.

Money in the stock market (or crypto market but similar) is probably the only way to justify tens of thousands of dollars worth of GPUs that become obsolete quickly.

The other thing I can think of is Reseach scientists who use it for research. But funded research scientists that I know generally don't get hardware to take home. They usually either get tons of cloud credits or time on a supercomputer to do their stuff.

> tens of thousands of dollars worth of GPUs that become obsolete quickly

I sold a 4yo gpu for more than I bought it for not long ago.

It's the only thing in a pc that doesn't depreciate much these days, besides maybe the case.

They wrote crypto in the original comment.

Ah okay missed it. So not QF. I was hoping someone does QF at home :P

If my hardware can do it, point me to how I can do it! I'll give it a try and let you know how you changed my life. ;)

Do you have a direct phone line to your local power company, and do you have to ask them for permission, before turning your rig on? :-)

Well, I can say that at $0.0875/kWh, it was a steal. I don't want to draw any conclusions about why they recently raised electricity price for everyone by 25%... But I'm suspicious that I and similar others may have contributed.

Swamp coolers for electronics?

Consumer electronics are designed for consumer living conditions. In many parts of the world, indoor humidity can sit over 60%, all year long. In a dry climate, you could get some significant cooling, and still be under what you'll find in my house.

Makes sense thanks

Phase change based cooling, especially when combined with a natural source of low temp air (such as a large basement) can be remarkably effective. Your typical DC has much too high a power density to be able to utilize this but for a single large rig in a home it could work very well.

In a dry climate the increased humidity still barely moves the needle and they’re extremely cheap to build and operate.

The humidity (in Utah) in that room was like 4%. Datacenters should be between ~45 or 60-80% humidity, depending on which source you read, to prevent electrostatic discharge. It was way cheaper than installing and running a mini-split. Plus, I NEEDED the added humidity.

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