You need 50sqm of solar panels just for a tiny 8RU server. You also forgot any overhead for networking, control etc. but let's even ignore those. Next at the 400km orbit you spend 40% of the time in shade, so you need an insulated battery to provide 5kWh. This would add 100-200kg of weight to a server weighing 130kg on its own. Then you need to dissipate all that heat and yes, 50sqm of radiators should deal with the 10kW device. We also need to charge our batteries for the shade period, so we need 100sqm of solar panels. And we also need to cool the cooling infrastructure - pumps, power converters, which wasn't included in the power budget initially.

So now we have arrived to a revised solution: a puny 8RU server at 130 kg, requires 100sqm and 1000 kg of solar panels, then 50-75 sqm of the heat radiators at 1000-1500 kg, then 100-200 kg of batteries and then the housing for all that stuff plus station keeping engines and propellant, motors to rotate all panels, pumps, etc. I guess at least 500kg is needed, maybe a bit less.

So now we have a 3 ton satellite, which costs to launch around 10 million dollars at an optimistic 3000/kg on F9. And that's not counting cost to manufacture the satellite and the server own cost.

I think the proposal is quite absurd with modern tech and costs.

Don't forget to budget power to run the coolant heaters and prevent them from freezing in the shade.

Especially if with the radiators you can just roll out as rolls of aluminum foil, which is very light and very cheap.

Only on a short distance. To effectively radiate a significant amount of heat, you need to actually deliver the heat to the distant parts of the radiator first. That normally requires active pumping which needs extra energy. So now you need to unfold sonar panels + aluminium + pipes (+ maybe extra pumps)

Orbital assembly of a fluid piping system in space is a pretty colossal problem too (as well as miles of pipes and connections being a massive single point failure for your system). Dispersing the GPUs might be more practical, but it's not exactly optimal for high performance computation...

It’s a fun problem to think about but even if all the problems were solved we would have very quickly deprecating hardware in orbit that’s impossible to service or upgrade