Yes, you will lose the warrenty, but (assuming you have a PII) as long as you don't do those wild modifications I see on the net to enable some clock multipliers, and don't have a small mound of melted silicon goo from over-zealous overclocking with the CPU running at 56.1V on an abit mobo with absolutely no liquid nitrogen cooling it. . . no one is really going to check close enough to see the difference.