I put a G0 quad (L728A) in my P965-S and can get it up to 9x390 (7 hours prime stable) but had to ramp up voltages all around.

Vcore: 1.472 idle / 1.440 load
VTT: 1.425
NB: 1.40

I've never been able to hit 400 FSB or over at any divider at any voltage without Windows rebooting as soon as I start Prime. Also, with the quad in, I have cold boot issues where it takes up to 4 or 5 restarts before the board will successfully post. Tried this with 2 different P965-S boards with the same results.