I want to perform a cheap CPU upgrade on an old Socket AM2 motherboard. I currently have an Athlon 64 X2, and want to upgrade to a quad-core AMD Phenom. IIUC, Socket AM2+ CPUs are backwards compatible with Socket AM2 motherboards. However, my motherboard (an ABit KN9) does not have a BIOS upgrade available to support this and is not officially compatible with any AM2+ CPUs.
At a technical level, what does the BIOS have to do with supporting specific CPU makes/models? What would be the likely consequences of installing an AM2+ CPU on this motherboard? Would the computer likely:
- Not even POST
- POST but not boot
- Boot but be lacking some important features
- Work with a few purely cosmetic issues
or something else?