I saw an article today that was talking about some cloud #hyperscaler - Google, I think - switching to a high-voltage DC power system in anticipation of supporting #racks with a power density of 1 MW.
A #megawatt, in a standard rack? I know Nvidia's selling GPU racks at 120 kW, which is much more than a traditional rack can handle, and there's talk about 250 kW, but this is 4 times more than even that. It seems ... impractical.
Doing a few calculations - a 42U standard rack is 600mm wide, a meter deep, and 2 meters high, for a total volume of 1.2 m^3. If that was a solid block of mild steel, it would mass ~9500 kg. In round terms, 1MW input would be able to raise the temperature of that almost-ten-tonne steel block from the freezing point of water to the boiling point of water... in one second flat.
The cooling requirements for a system like this would be prolific, but I think it would require some never-seen-in-computing changes as well, like a "thermal crowbar". Just as a crowbar circuit shorts the power to cause a breaker to trip when some failure condition is detected, you would need something to immediately kill power to such a rack if the cooling system was impaired at all. You don't have time for this to take ten seconds!
They're also talking about it being an 800VDC system, so you need 1250A. For that, you would need a copper busbar with a cross-sectional area of more than 500 mm^2...
This doesn't smell right.
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