CPU voltage issues

So there I was overclocking my Q6600, setting the voltage to 1.30V (was originally on "auto", HWmonitor, SpeedFan and CPU-Z all say I'm at 1.30V). However, all is not well - something screws up when I manually set it to 1.30V in the bios. It doesn't load Windows and my latest and greatest error was "bootmngr not detected" or something exciting like that. When I put it back to "auto", the problem is gone.

One thing worth noting is that when I did successfully set the voltage manually earlier was that the bios voltage didn't match with HWmonitor, CPU-Z etc etc. It was a good 0.2V lower then what it read in the bios.

What's up? D:

The voltage read by software in windows always seems to be lower than the voltage in the bios. My voltage is set at 1.3625V in the bios but various software reads it at around 1.34V. I think this is normal, if you set it manually to say 1.32V it should run stable.

Ah I see, thanks. I was just worried if I had any major problems.