Summary: I have an old(er) Mac Pro 3,1 that was running the original 8800GT and was chocking a bit in the newer games (Borderlands2, Bioshock Infinite, etc) and needed something with a bit more horsepower - even an upgrade to a Radeon HD 6870 wasn't cutting it. Luckily the GTX680 has drivers available for both OS 10.8 and Win7. Works great under Boot Camp, just needed a DP to mDP adapter to get it to work with Apple Cinema Display.
Summary: Before this card, I owned a GTX660TI Twinfrozr, as well as an EVGA GTX680 and I have to say, MSI makes a beautiful card. On max load, my EVGA got up to 70/75C within the first 30 minutes of playing, so I decided to return that for this GTX680 Twinfrozr, given that I was pleased with my 660TI Twinfrozr, and wow, I am not disappointed. I've been playing Grand Theft Auto 4 all day on this bad boy and haven't gone above 60C. This is a great card, runs cool.
Summary: This card is a dream. Currently overclocked to +150 Coreclock and +500 memory clock, and its completely stable and hasn't gone over 60c after a 3 hour stress testing. The fan isn't that loud, and cooling is amazing. All I want is a second one.