manic

Corsair makes a very good psu. But I think your underpowered with
that one. I would be running a 750watt corsair. If the specs Ive read
on your 520 watt are accurate, you have 3 12volt rails @18amps
which is enough power, but figure in the efficency, and age of the
unit, you are pressing it. That can cause overheating. You may get
by with the 650watt, but for a few bucks more go for the 750.

If your careful you can remove the cooling block without draining the
system, clean both surfaces with alcohol, then reapply making sure to
do it correctly, to much grease is not good.
The radiator should not be getting smacked by hot air escaping from
your machine. The fluid can only stay as cool as its surroundings. If the
radiator gets hot, the fluid gets hot. Might have to do some creative
management for the radiator. Are you sure there are no air pockets in the
line?
Never a big fan of water cooling,,,