I've just replaced the 2x 5770 in my Mac Pro with a single GTX 680 twin frozr. Everything is great, I have the latest 10.8.2 Nvidia drivers installed but my PCI fan now runs at around 1350RPM! With two 5770's I was getting a speed around 900RPM. Anyone know why? I'm reluctant to use SMC fan control etc as it should be controlled by the system, everything else is good.