I have recently bought an MSI 4870 with 1 GB of GDDR5 (T2D1G model) in my mac pro, only for the purpose of using it in Vista and playing games. I did understand that its not supported in OS X, and even if i use the stock (2600XT) card to boot OS X, it will spin its fans at full throttle. I installed the 4870 in the first PCI slot, but i didnt have the proper power cables for it (only one mini6pin-to-normal6pin, and one 2x4pin-to-normal6pin) so i just tested it in Vista for a time, without even putting in the 2600XT and booting in OS X. Worked like a charm, with Vista automatically booting all the time. But today i got my other 6-pin power cable, so finally i could close the side panel, and put everything in its final place, with the 2600xt in pcie slot 3 and the MSI 4870 in slot 1. I booted os x for the first time since i installed the 4870 and for my greatest surprise, the fans are spinning at a normal, barely audible rate on it!!! How is this possible, and is this a normal thing, ie. won't the 4870 overheat because of this, or something??? System Profiler says the following: Should i be concerned, or just cheer, for i can now play games in Vista and use OS X without having to hear the very very loud fan noise?!