I want to upgrade my pc's processor from AMD Athlon IIx2 to AMD Phenom IIx4
as far as I know when you install an operating system, the hardware specs of the PC is being save in the registry
can I change my processor without formating my PC again (will it malfunction because the processor specs on the registry doesn't match with the system's registry?)
If your mother-board support the AMD Phenom IIx4 processor only then you can upgrade the processor. Actually os reinstall is required when every time you upgrade or install a new hardware into your computer. But some time the system configured without any problem. But you need a back up for your important data. Then you can try this process.