If you're going to do any bios updates, its best to leave the PC as it was build. Proceed to the Dell support website and using your service tag#, enter it and then its at the right support webpage. The data there is the most current and dealing with bios, what's there is it. I wouldn't push it or go elsewhere, because that's the best info to have. No matter what other info you find, if you bios update wrongly, you're creating a "brick". Also, I strongly urge you to review the exact instructions if you proceed and print them out. Also, don't do any online bios updates. If you bios update and it all works, 100% then go and swap cpus out. Of course, the new cpu MUST be supported even if the bios update was done, there is a limit of cpu supported. To correctly ID the right as well the proper cpu class & type, the cpu makers usually supply that data, so review it. Use CPUID pgm. to quickly ID a cpu. Alas, its maybe better to totally remove cpu in hand and wipe compound to read the stock# which is the absolute solid way to ID any cpu chip.