Wow. I thought even the bad E8400 chips could do 4.0 with no problems.... what are other people getting with this chip?
Try going to 420 x 9... then 430 x 9.... then 440 x 9.... then 450 x 9.
Also, try changing the Performance Enhance option (I don't remember the exact name)... the options are standard, turbo, and extreme...
Oddly, I'm stable at the turbo settings. I read an article somewhere that said the standard setting gave the fastest performance.
Even though my ram is stable @ 880mhz with my cpu @ 3.6ghz - I still am leaning towards my ram being the unstable factor when i get the cpu up to 4.0ghz