I've been the proud owner of an MSI K9N2 Platinum motherboard with an AM2+ socket for a while now, and I'm in the process of upgrading.
Will an AMD Phenom II X4 965 processor work with my motherboard?
The reason I ask is I've read from less credible sources that AM3 socket processors can be used (in DDR2 mode) with motherboards with a AM2+ socket. I understand that a quad core 3.4 GHz is slightly overkill in a DDR2 system, but I'm just slowly upgrading. My BIOS is at the latest version.
It should work together, and I might suggest upgrading to an AM3+ board after a little while, then getting a Steamroller chip. Unless you want to swap to Intel, then you have different choices to make.
Normally am3 is backwards compatible with AM2+ socket but there is also a motherbd bios component to consider. Without bios support a processor will probably not work so even if you had an AM3 socket you would still check the motherbds supported CPU's list. In your case I've checked and yes it supports the 965. http://www.msi.com/product/mb/K9N2-SLI-Platinum---K9N2-...
I am running an AM2+ socket right now with the Phenom II x4 965 OCed to 4.0 on ddr2 1066 ram. It will work but like "popatim" said make sure you have the latest bios update and you will be fine. The 965 only supports speeds up to 1066MHz for DDR2 ram though. Every time I have tried to go over that my system would become choppy so figure for max of 1066Mhz and if your really lucky you may get more.
update the bios before installing the 965 just to be sure it will boot right away.