Does this board have 3-phase power? The p5k deluxe has 8-phase power, and the Gigabyte p35 dq6 has 12-phase power. Phases will obviously make the CPU voltage more smooth in delivery which is what quad cores need.

Ive not seen any specs concerning the p5k vanilla, but in the pictures Ive seen I can only see 3 PWM in the place where the higher end boards have their heatpipes.