At 475FSB on the older bios files P1P2 seem to get disabled, you see this by the read speeds in everest taking a severe hit, writes looked to be uneffected. Now a few reviewers asked for what ever was happening pre 475 to be given back in options the end user could enable or disable, hence you see P1P2.

Now Nvidia can change P1P2 performance where ever they like, it could be now 500fsb before it gets disabled or 450...its just a simple hidden command but at least we now have the option to manually force it.

I do hope this clears up what i was saying about P1P2 switches.