eva....Got my P5K-DLX last nite and been playing.
I've noticed that the voltage damper is more effective with dual core than quad.

e.g. With 9 x 333 Bios set at 1.20 gives 1.168v idle for both cpu's.

E6600 @ 3000 = 1.160v under load
Q6600 @ 3000= 1.152v under load

All measurements from cpu-z for reference.

Have you noticed the same?