In general  mosfets would produce 20-30% of load. cpu power usage in this case.
 
but its mosfet, so the more you increase the switching frequency the higher the power usage.
 
I'd say between 30-60% of cpu power just to be safe, I know asus bios really allows you to ram up the switching frequency.
 
Expect couple of degrees increase . remember, 4770k gets really hot because of the TIM not because its super power hungry.

A mobo block will not effect it too much, a mosfet block can drive the loop temp up some.  Low-mid 30s is a bit warmer than average for water, but then again, what are you clocked to?
But in the end, idle temps can provide some baseline, but they aren't really that important to actual functionality.  I would run IBT and see what your temps are, use your motherboards monitoring tool to watch what your VRM temps are, and Realtemp for the CPU, and lets see what your temps are under heavy load. 
Also, from personal experience, while MOSFETs/VRM can get REALLY hot before an actual component failure, VRM getting hot can REALLY have an adverse effect on system stability, I got my VRM cooled back down on my X58 and all my stability issues went away.
 
In the end, will it have an effect on the absolute best temps your CPU can get, yes, is it a big deal, no not really, and in the end you can potentially be more stable due to keeping other important components cooler as well.

Thanks Guys. I'll do some testing tonight and post back. Worst case, I'll have to reapply indigo extreme or go back to Diamond Paste.

I'm going to reapply Indigo Extreme and see what happens tonight.