Main way to know is socket type. Every processor is manufactured to use a certain socket, and require a motherboard with that socket. The motherboards BIOS also needs to support th processor, which most motherboards get updates when a new set of processors are released for that socket, unless you have a prebuilt since they usually lack updates. Then some budget motherboards can't support high end processors, by this I mean they usually will support only 95W processors and top end processors are frequently 125W.