Hope this video helps some of you. Heat was one of the last issues keeping me from ordering a new iMac. I hope the comparison in the below video is typical of all 2015 iMacs: Conclusions: 1. 2015 GPU runs about 10-15% cooler on identical load tests 2. 2015 GPU runs about 10-15% cooler on identical load tests 3. Apple has apparently implemented new fans and/or software that ramps up fans quicker Shout out to Max Yuryev! Excellent video!