Hi again people, As you may be able to deduce from my recent posts I'm currently playing around a bit with my 2009 4,1 with 5,1 update. I have recently installed a flashed XFX 5770 and despite probs with known issues such as pci fan speed and display port output was pleased with how it was working. The general computer however was a bit temperamental but not unusable. This is probably where I get my noobiness explained to me but I thought that maybe a cleanup would help and ran it through a basic Onyx maintenance run. HD verify, permissions check, general clean up. Having done this I've now lost boot screens on the 5770. The GPU fan spins up really fast on boot and runs fast throughout operation (although perversely the pcie fan now runs at the normal speed). This happens when booting on both the drive that I've run Onyx on AND my other Sierra boot drive that was in the machine at the same time..... So I'm a bit worried about what has been been 'fixed.' Couple of other people seem to have mentioned it happening but I've not yet come across a solution. I'm running a new installation of Sierra now to see if that helps but any thoughts as to what else it could be? Might it have messed with the 5,1 EFI flash or something? Once again thanks for looking and helping out.