I beat you all, I have 2 IBM motherboards that boot only if you hot swap the processor from a Core 2 Duo to Pentium 4.
During 2 days I tried everything possible with those 2 same boards, thought impossible that both weren't working.
Never wanted to boot but then I found the trick:
Start with a C2D (Power on, fans on and so)
Shut it down (by power supply switch) shut it on just after
Eject the Core2Duo, place the Pentium 4 very very quick
Hit the reset button then the motherboard boots and allows you to go in the BIOS and boot Windows.
^This is the ONLY way to boot the board
True story!
U CAN'T TOUCH THIS!
Did all of that only for 1 gold cup/ 2 hardware points