Lots of discussions on how important the board and the VRMs/etc are on ocing.
It is pretty well accepted that they play little to no role in the CPUs OC ability unless running dry ice, ln2, or other extreme cooling options. That said I bought a $300 board anyways
but I like having bells and whistles... not that those bells and whistles make my computer faster.
For water cooling I would guess that the Asus Gryphon and Sabertooth are the best boards simply because you can take an inline coolant sensor plug it into a header on the motherboard and control the fan speed of your radiators based off the actual temp of the water instead of the temp of the CPU. Why is this important? Because when your cpu temp spikes for a few seconds it doesn't effect the temperature of the water enough to warrant spiking the fans... when your cpu temp is going up and down up and down in a video game your fans are going up and down up and down which is annoying... also just because your cpu has cooled down doesn't mean your water has cooled down so your fans should still be running to cool the water down.
In retrospec I wish I bought one of those 2 boards... it was just hard getting over the price when you compare the power delivery setup on those VS other boards of the same price... like I said though the power delivery has little to do with the OC on water and air.
This doesn't hold true for your AMD board and CPU because that CPU draws tons of power and there are boards that don't supply enough to OC it. All of these decent boards provide more than enough power for the Intel CPU since it requires so much less.