Overclocking help needed

I have Abit IS7 and P4 1.8a that I want to overclock to 2.4ghz. I do this and set voltage to 1.775V and it passes the 6 hr CPU Hot Tester fine. However it cant get thru a single loop of 3dmark2k3 at these settings. What you guys think is up? FSB is 133, memory is 166, agp/pci is 66/33. Oh i'm using ATI Radeon 9800 Pro and 2 samsung stix DDR333 in Dual Channel.

cpu has probably hit its maximum