hmm...
water cooled PSU, I've seen it tried on an amature scale to disasterous effect.. but some of the implimentatios around seem workable.
Personally the PSU is one part of my system I would never get water anywhere near. Too much at stake, if the PSU goes and starts throwing 240v down the wrong rail... well... *shudders*
CPU, GFX, NB, HDD, MOSFETS, RAM and Soundcard are all viable recipents of the old W/C, and even a 120.3 with 6 fans push/pulling would be feeling the load under that.
PSU's are all designed with sufficent cooling to dissapate all the heat generated, all the way to their maximum load (if not then legal action come into play). I have my PSU drawing air from outside my case, and exausting it outside as well... its a completely seperate cooling situation to the rest of my PC.
The heat dump would be intense, so we're probally talking seperate loop stuff here, or at least another radiator 1/2 way round a loop to ensure the water is cool enough to deal with components in order. I'd feel the need to make sure I had cooled (at least ~ambient) water on both the PSU and the CPU, hence multi-loop, or two (even three) stage cooling.
/discussion