This is just in case anyone searches on this obscure problem. I recently upgraded to an Asus A7V333-RAID motherboard with onboard audio. I use a CH Product Throttle that has an inline keyboard PS/2 or AT connector to inject keypresses into the keyboard interface.
This seemed to be causing the PC to fail to see both the PS/2 keyboard and any PS/2 pointing device (No Keyboard Found on system boot).
The fix was to disable Keyboard Wake Up (KBWK jumper disable). Page 23 of the Asus manual.
