Crazy motherboard problem

Hi,

I've got an Asus P4B266, and it's got a crazy problem

Problem is the board is recognizing only one CPU - an old P4 1.6A. I used to run it with a P4 1.8A, but I don't get a display with that anymore; fans spins and machine powers on and off, but no display.

Everything is fine with the 1.6A. Tried with a P4 1.7 GHz, but no luck.

Tried flashing the BIOS and updating it, but it's the same.

How come the board runs only with that particular CPU? It doesn't even work with a 1.6A from different batch/stepping.

Please help!

Some Asus boards are very picky about swapping CPU's, so did you try clearing CMOS when putting in another CPU?

Sir Lancelot,

Already done so.

No improvement.