Computer Force Restarts?

I am building a new computer with a Leadtek k7ncr18gpro2 mother board,
AMD 2700+, 512 PNY memory. I intalled XP professional and now when I
start up it will only take a few minutes until the system forces a
restart and automaticlly restarts on me. I am not sure what is going
wrong? I was wondering if this could be the fault of the motherboard?
The problem seemed to arise when I set the FSB to 166, but I am not
sure if this is a coincidence. Someone please help me out...Thanx!