Thanks for the compliments. =)
You should only need watercooling if you are running your cards above stock settings, such as when overclocking and overvolting. Otherwise, the stock fan should easily be able to keep the GPU from overheating even at full load.
I have no experience with the HD 7970, but @vortac is an expert in those as his entire research operation is centred around watercooled rigs running several HD 7970 cards. He may be able to offer some more insight. =)
Thank you for the answer :)
I wouldn't OC the cards because it would consume too much power.
I looked at @vortac post with his quadro HD7970 watercooling. Lookes pretty nice. Thank you for the hint :)
Hello @jexkin and welcome back to Gridcoin! Watercooling should be considered for multi-GPU rigs (can be very difficult to aircool, unless you intend to build a mining rack in your basement).
Watercooling is also useful if your mining rig is going to be placed in the living room or anywhere else where constant noise might be an issue (water will practically reduce operating noise to zero, while allowing massive overclocks).