Ah sure, another HS/peltier combo... looks nice though. Someday I'm gonna have to get myself a chiller.

I tried to hit 500FSB aswell in the meantime, the good news is, I hit 490x7 w/o a problem, bootet right into windows and was even 3dmark stable.
However, I can't seem to get to 500 no matter what. I guess the CPU doesn't like it or whatever.
Anyhow, one major point: ICH voltage seems to be crucial for QC overclocking, at least for me (as it was on my old QuadGT)
I tuned down every single mobo voltage for 400x9 and all went well, until I set ICH too low. 1,05 gives pirme errors (custom blend - inplace) after 1 minute, 1,10 gives a nice BSOD (IRQ not less or equal) after a couple of minutes, 1,15 is primestable but crashes if I run BOINC and CoD4 simultaneously () and 1,20 is rockstable.
Oddly, I observed this behaviour with various boards and a few different quads (B3 and G0) so watch the ICH voltage if you wanna get your rig really stable.