Right, so I did that... and I found out it's a Dell 0FJ030. According to the forum in the site below, my XPS 400 desktop's motherboard can't have any Core 2 Duo processors because those chips require a different "voltage regulator", which makes sense I suppose.
Here is the issue, the board that is used in the Dell XPS 400 uses the Intel 945P chipset. This chipset does support the early Intel® Core™ 2 Duo and Intel Core 2 Quad processors with a Bios update. The problem with that is a number of the OEMs didnt release that update for their boards. Dell does state that the board that you have supports Intel Pentium 4 and Dual Core processors. So it is looking like it will only support the Intel Pentium D processors but to get any more detail then that you are going to have to talk to Dell.
It's not as if you're overdrawing, what you're upgrading to uses less power. As far as the voltage is concerned the max the p4 could handle was 1.4v which is still within the useable specs of the c2d. I don't see an issue.
edit: With all that being said, I'd take Mr. Woods advice, lol.
Thanks for the response.
Dell was actually the first place I went looking for answers. Both their sales rep and their tech support gave me contradictory answers, which is what prompted me to go looking on here for 2nd/3rd opinions.
At first, they strongly recommended against it because they said "it would cost them too much and you should buy a new computer." Then they said that the sockets weren't the same, to which I responded that I had actually pulled the chip out and was pretty damn sure the sockets ARE the same.
Then they said that I shouldn't do it because it will draw more power form the power supply. (Since I was also inquiring about a video card upgrade, this was a valid concern at the time.)
They never mentioned BIOS at any point as being a reason for concern. Assuming there is a BIOS update, and that I buy a NEW (not 'early', as you said) C2D, should I expect any problems?
Also, where do I go hunting for this BIOS update? I want to make sure it exists before I buy the chip.
Tyler, here is a quick chance to see if you can get it to work. The Intel® Core™ 2 Duo's were lunched in Q3/06 go to Dell's site and check to see if they have a bios release for q3 or later of 2006. If they do it is a good change that it enables support for the early Intel Core 2 Duo's. You need to make sure that the processor that you select (Intel Core 2 Duo is a 65nm processor like the E6300, E6400, E6500 or E6600 or maybe the Intel Core 2 Quad Q6600).
In the end the only sure way is to put the new CPU in and if it doesnt work you have to go back to the old one.