Ok, so I've found the CPU of my dreams (INTEL PENTIUM 4 3.0GHz Socket 775 800MHz 1MB) but I'm pretty sure my MOBO will not take to it as I have, at the moment I have an MSI 645 Combo, not only does this have a 533Mhz FSB but I dont think the CPU will fit, how do I know if that CPU will fit the Motherboard I want, I'm looking at a GIGABYTE GA-8I915P Duo Intel 915P LGA 775 motherboard. Can any one tell me if its compatiable, or even how to tell, thanks. Kind Regards,
Dan

The Socket tells all(except for the FSB, which is compatible as well.). Basically, the motherboard is Socket 775, and the Processor is Socket 775. The number, IIRC, refers to the number of pins on the processor. So yes, the two products should work fine together. Just be sure to get a good fan.