After overclocking FSB, no vga...........   

I have a self built box running xp pro.  i overclocked my fsb and rebooted.  
after rebooting, i have no vga at all.  How do I reverse what I have done and 
restore my vga.

date: Tue, 30 May 2006 18:10:02 -0700   author:   overclocked fsb, lost vga overclocked fsb, lost