My #2 machine is very similar to yours. PhIIX4 965BE @ 4.0 GHZ w/212 EVO, MSI 785GM-E65, R9-280, 750W PSU. I got it to 4GHZ with nothing more than the multi at 20 and the core volts at 1.4 I left everything else on auto in BIOS. It passed prime95 and Intel Burn Test.
Go here and scroll down to "overclocking tips": http://www.bjorn3d.com/2009/08/phenom-2-x4-965/