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Comment by nkingsy | Hacker News Reader

People talk about cards not being worth the electricity vs cloud. Seems like an a100 pulls 300w, costs $1.50/hr ish to rent, and costs $12,000 to buy, meaning it pays for itself with 1 year of constant use.

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Sounds like a business opportunity. Of course, the risk is that by the time you make your money back, the cards you've been renting to customers are obsolete and you need to recapitalize...

Labor and infrastructure add much more costs. But I'm sure with the current hype they are all making bank.

Most of the new providers are putting them in liquid cooling to cut down on electric.

Why would liquid cooling cut down on electricity cost? The only difference is fan power vs pump power -- is it really much different?

If I had to guess the difference is made in building cooling, not per device.

It is much easier to transfer X amount of heat with a liquid than with air. Liquid travels in pipes and has enormous mass heat capacity (Per unit of volume, water has about 3200 times the specific heat capacity of dry air (at 77°F)). Air needs wide straight ducts and fans every 10 meters to keep air flowing.

Sure, but removing that heat to the outside still takes the same amount of energy. Unless they just pour the water down the drain it has to be transferred somewhere, no?

Wouldn't that depend on the sink? If they can cool down to the water, then running a water-water-heatexchanger would require less power (due to better heat transfer) than simply cooling it to the air.

Same I guess if they could use evaporation to do some of the cooling.

Just seems like a really complicated setup to use unless you were going to be saving enough power to make all the complexity worth it. Remember you have to put a water block on each card and design a pump and piping system that will run through all of them.

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