lol, PSU'S don't give off much heat? Yes they do...lol
Converting AC to DC constantly has an efficiency rating. Normally most PSU's are 70%, better ones are 85%. The remaining portion of that percentage is "waste - aka HEAT". PSU's always give off heat. If they don't, you've got a problem.
I find it hard to believe that you are going to use water cooling with that case. It's not that I don't believe you, it's just going to be very difficult in a case that's set up like that.