I spent some time this afternoon OC'ing the QX9650. I found the Maximum Extreme a little tricky to work with, but not nearly so tricky as the Striker paired with Quads.
I was making scant progress -- stuck at 390 MHz 9x -- until I bumped the vdimm a bit. As noted earlier, this board overvolts the vdimm by .08v. Super Talent cautioned me about running too much voltage through the DDR3 -- that it will drastically shorten it's lifespan. I've heeded that advice as much as possible, but have found that with the RAM I'm using (suggested vdimm 1.9v), setting vdimm between 1.86 and 1.90 in the BIOS seems to be the 'sweet spot' for overclocks between 400MHz FSB and 444MHz FSB (3.60 GHz and 4.00 GHz). So, this puts actual vdimm between 1.94 and 1.98v as providing the most stable overclocks in the range noted above.
I manually set the NB Strap to 400 MHz and found that performed better than the more popular 333 MHz strap. DDR3 was running at 1780MHz @444 FSB (a 34% OC).
NB voltage was set to 1.53v and CPU vCore voltage was @ 1.50 at all overclocks. Temperatures average 39-42C at idle with no overclock and 43-47C idle running at overclocks between 3.60 and 4.00 GHz.
From what I've read on the various forums, these initial overclocks are modest, but a good place to start.
Here's a quick screen capture: