I have live Ubuntu (tried also Mint and Kubuntu, same effect) on a USB stick with persistence enabled. My laptop is however very noisy (VGA still on max?). I solved this problem before back with Mint 7 Gloria like:
Ctrl+Alt+Backspace (restart xserver). VGA then behaved reasonably.
I can not reproduce these steps anymore with latest Ubuntu/Kubuntu/Mint.
Can the problem be that I'm on a LiveUSB? Is it normal, then when selecting "Additional Drivers" for nVidia they always fail to install (those proprietary)?