Re: Heat pipes may offer a better solution
This is the best compromise. There are already sime high end gaming machines that I've seen with self contained liquid cooling. It just circulates from the main processor and graphics card to a radiator at the top or back of the case. For racked servers, it would be a simple matter to have an ordering option for a liquid to liquid exchanger. The board components (other than the processor) can be cooled with a small internal fan and heat exchanger to the cooling loop. The air inside the case would be a closed loop, so no dirt and dust.
Racked servers could be connected to a liquid cooling loop with quick disconnects (similar to what is available for garden hoses). So maintenance, including swapping out an entire blade would not involve going elbow deep into a fish tank. Less coolant would be needed, as most of the server/rack volume would be air. And the coolant would be contained within a loop. So less concern with flammable liquids or weight when adapting to existing building structures.