How can I upgrade my Dell XPS 400 to Core 2 duo?

most likely you can't

but check the manufacturer's site for supported processors

The answer is no... sorry to say, you do have the 945 chip set but dell has it compents made for dell, in the case of the dell motherboard will not recognize the core 2 duo processors... check the forums on dell, you will get the same answer...

that's a reasonably severe-high quality device even with it being a Celeron. My guess is which you have something working like antivirus or quite some information superhighway homestead windows or undercover agent ware/viruses working in the history and that's borrowing processor time from the game and inflicting lag. you will desire to attempt turning down the game's video settings. decrease determination, much less component, etc. could provide you a greater constructive physique fee, however the image high quality does not be as stable. i certainly think of the game is having to share the processor with something else that's no longer playing honest nonetheless.

Your motherboard uses an Intel 945P chipset, which supports Core2Duo, and has the 775 pin CPU socket. You'll void any remaining warranty, but it should be a drop-in replacement for Core2Duo processors with the same FSB as your Pentium D.

You might need to upgrade your BIOS firmware.