There might be a Bios reset on the board. Which can restore the Bios to native configuration. This most likely is a jumper change. Once that happens put the Intel® Pentium® D in and run CPU-ID on it and come back and give us the information as to what the board is and we can go from there.
CPU-ID is a freeware program that you can run on your system that will give a list of the components within your system including the stepping on processor and the motherboard and what chipset it has. CPU-ID is a free for download and is well tested application for helping you find out information about your system.
Conroe is the pre production name for the Intel® Core™ 2 Duo processor, 1333 would be the FSB that the Conroe could support and d667 is the memory that would have been supported with an Intel® Core™ 2 Duo processor with a FSB of 1333.
So just off the top of my head this seems to be where the is, while it is possible that one of the OEMs may have upgraded a 945, 955 or 965 chipset based board to support a Intel Core 2 Duo with an FSB of 1333, I would be a little shocked if they did. And the 3 and 4 chipset series boards that did support the Intel Core 2 Duo with an FSB of 1333 don’t support the Intel Pentium D processors.
The fans, hard drives etc running just lets us know that the board is getting power and that there is a processor in it. If you put a processor in that due to increase voltage fired connect to the PCI-E 16x slot the board or the onboard graphics it would still get power but wouldn’t allow any video signal out.
The reason to reset the Bios is hoping that the board isnt fired but there was some change to the bios that is causing the problem.
That is what I am thinking/hoping if we can reset the Bios with the old CPU we can get it up and running. Most of the time when I have talked to people who have put a processor in that isn't supported it doesn't boot and may not post, but in this case who knows how the board might have reacted.