What determines whether a processor is compatible with a motherboard? Is it just the socket type? Or are there other things to consider as well?
Processor compatibility also depends on chipset revision. For example you can install old sockect 775 Pentium 4 in new Core 2 board but Core 2 will not work in old Socket 775 board due to difference in chipset. Processor compatibility also depends on motherboard BIOS which supports processor you want to install. If there is no new BIOS for your processor then that will not work in your board.
On top of what RAK said, there is address registers (32-bit or 64-bit) and memory controller location that needs to be compatible as well. Newer processors (Core i7, Athlon 64) have an integrated memory controller, while on older ones it was located on the motherboard.
Thank you for the answers. I understood everything. Except for Address registers. What are address registers?
You do not need to be worried about address registers as majority of CPU in market except old P4 and Celeron are 64 bit, which mean you can install 64 bit version of windows and other software on them. 64-bit address register CPU are in producrtion since 2003 so no need to worry about that.
Can I find whether mine is 32-bit or 64-bit?
go to the manufacturer's site and search for your model. that info will be provided there
^ Or you can check it with CPU-Z as well.
In which tab?