I recently put a Mobile Athlon XP 2400+ into my asus a7n8x-e mb. My BIOS is set to an external frequency of 133 MHz (FSB=266), but the max I can get it to is 1.6GHz (12.5x multiplier). When I try to set it higher, the speed drops to below 1GHz (a 14x multiplier had it running at 800MHz!

. Why is this? How can I fix it?
Chris