450MHz FSB ? If yes, then yeap, PL5 is good for that FSB

p.s. Just tested all the CPUs that I've got here on the X48T-DQ6 rev1.1 hoping for 1 of them to reach higher FSBs than with the P5K3D...but I got nothing
Max FSB 517MHz...

Gonna grab a E8500 more than likely off a store this week.