@A-Grey
I wouldn't be the least surprised knowing asus to find that there is a problem with the clock skews and high fsb.

I've read a post by mikeyakame in the GTL settings thread where he got his quad q6600 to an FSB of 483 i think it was on bios 701 so with no clock skews on the rampage formula. I'm not sure if his board is unique but i do know he was using a vNB of 1.6-1.7 but it shows that it is possible. I have his bios settings if your interested.