I have 4 x 7970. They constantly overheat causing my PC to shut down.
I have previously tried to cool them with a stand-alone fan blowing through a copper coil filled with water.
This way is not so efficient. PC still shuts down.
I am putting up bounty [1BTC] for the best idea on cooling.
Maybe there is someone out there who's got it figured out.
Thanks for participating.
Simple. Get a high cfm/high static pressure fan, and mount it on the back of the case. The fan on the 7970 is designed poorly it seems like.
My case comes with a fan box that goes on the back for the gpus. I used it with my 7970's on air and it caused a massive temperature drop for them. The fans on the cards barely went off idle while mining they were running that cool. You should be able to build something similar.