回答“What GPU's are compatible with iMac 27" 2011?”My cure was marked as SPAM by the automated filter because I included two links to Amazon web pages where I bought the parts. Here is the fan for the back of the iMac case: ELUTENG-Cooling-Cabient-Ventilator-Receiver|A simple cardboard V shaped vent cover and package tape is all that you need.] Very moderate (below 50*C on GPU, CPU, HDD) temps showing on the MacFan app. Almost silent--I can't hear anything, and I have good low volume detection. Here is the vent fan for any laptop heating problem: Coolcold-Portable-Adjustable-Performance-Controller Coolcold Ice Troll III Very effective, not too loud, detachable, speed control, 3 lips sizes] I got this after my Lenovo G555 had video chip detachment from heat after 3 years and I put in a new motherboard. My Dell R 15 3521 Inspiron runs at 90*F or less all day with one.