I have the P5K-E asus mobo.
and its not the mobo that is limiting the FSB...my friend as the same spec as mine different cpu batch ,borad is limitng him at 480... and some borads can do 500 with not much truble...well it's my Q6600 that doesnt want to go any higher... well for now i'm running 24/7 3.2 rocksolid at 1.304V no more than 50C load. so i think i'll just wait maybe later i'll upgrade the CPU or the entire rig...