That should be enough if you don't need to up the voltage a lot pushing the limits to get the CPU to 5.0.
1.42V on CPU for 5.0Ghz...And 1080ti OC to 2000Mhz... Max rad support for my case is 1x420mm/60mm and 1x280 mm/30mm
Kraken x62 AIO watercooling is kepping temps at bay with this clock...Thats why I asked if one 420mm than would be enough in custom loop for this CPU and GPU....