Asus does state that the P5K Deluxe is a very good overclocking motherboard. The BIOS includes all settings to boost the CPU's overall speed, either by increasing the FSB or RAM frequencies. We had some problems with the 0311 BIOS. However, the newest 0404 BIOS solved all our issues. Ok, so this motherboard can overclock. The real question is by how much.
Without making any special effort and leaving all voltages at auto mode, we managed to get a 100% stable 484FSB with memory running 1:1.
That was a very good performance! Asus Commando with exactly the same components reached 480FSB. Perhaps with a different CPU, like the Intel E6300, you can get even more FSB "juice" from this motherboard. We have seen reports reaching up to 505MHz FSB. In any case, this motherboard can overclock.