For the people with Asus P6T boards : watch out for 'AUTO' settings and overclocking !!
If you leave everything on auto and start pushing the BCLK , the voltages raise automatically . I've caught my DRAM voltage at 1.66vdimm () , QPI/DRAM 1.3v , PLL voltage also very high IIRC.
There's a nice tool called 'turboV' , that's how I noticed.

Best to set these voltages manually before starting overclocking !
It's pretty difficult and confusing when you're new to core i7. But don't worry , here to help