Convery, how did you manage to be able to adjust the voltage?
Well, Sapphires forums and reviews said that you couldn't increase the voltage but I just opened Trixx (Sapphires overclocking tool) and adjusted it. Only bad part is that my 7 year old PSU exploded =P
But with my new PSU the maximum stable (and what I use) is 402Mhash, you can go up to 430Mhash but then you bluescreen after a few hours and my computer is being a bitch when it comes to rebooting.. Also the card never goes above 65C and is placed without a chassis right next to my bed so needless to say it's quiet enough :3