I've updated the Motherboard's bios to a realease from late September. This has seen a slight improvement in the reported figures but not performance. The clocks will drop to 600/900 every three or four seconds but immediately revert back to 850/1200. The GPU load is now at 0% but spikes to 21% every five seconds or so. Both of these are at idle. All the playback and performance issues remain. I've tried turning off aero, not installing the ATI audio drivers and video playback in VLC - while the problems differ slightly (more flickering in Media Play and more stuttering in Quicktime) it is far from satisfactory. I'm going to have a detailed look through the bios to see if there are new settings to adjust.