You won't be able to get the PII400 very far because it is already on a 100FSB, and the L2 cache on a PII is not on die. If you want, you could go and get a celeronII566 and OC' to about 850 (some will hit 952 with a 112 FSB). I believe that if you have the BH6 Revision 1.01, then you could pick up a Pentium III and overclock that, because you could go to a 133FSB because in the revision 1.01 they allowed a 2/3 agp and 1/4 pci bus divider. The Celeron 566 would only cost you about $55-$60 shipped.