There's no way I'd spend the money on a new CPU and hope that a "unofficial" bios upgrade would work. I believe there's some electrical requirements that the 965 just doesn't have.
Take a look at this combo from NCIX.
NCIX.com - Buy AMD March Madness Phenom II X3 710 Triple Core Processor & MSI DKA790GX Motherboard - X3-710-790GX In Canada.
$260 for a 790gx board and 710BE seems like a good deal to me.