80 C is fine imo
water cooling is stupidly expensive
I am so paranoid
, so I try to keep temp below 80.
yesterday I tried to lower cards voltage, and surprisingly I can run all my cards @ 1.05v when mining scrypt coins compare with 1.065v while mining BTC, so that give 4C lower on each cards.
water cooling is expensive, but if you do it the cheap way it won't bite you too much. I managed to do it like this:
I played swagbucks and other mobile apps that will allow you to exchange amazon gift cards for about 3 month (from Jan to Mar) , so I end up with about $120 in my amazon account and it covers an Koolance 450 water pump and triple bridge
Now I have enough for a 360 rad and some tubing, fittings, but I still need to spend about 200 for 3 GPU Core water blocks, too bad no sellers at Amazon carries that
So I am waiting for the next BTC price surge....... hopefully before summer is coming