well, I got sick of Windows 7 and put XP Pro x64 back on my rig, which seems to have removed the problems I was getting (who knows why, my rig is more than capable of Win7.) Since doing that, I've encountered a new phenomenon...
This is a screenshot of CPU-Z from yesterday
See, it's reading the clock speed as 3.36GHz, and it is clocked at 2.8GHz by factory default and I haven't overclocked it myself. Any idea why this might be?