This would be an epic resurrection of a zombie thread, but I'd hate to leave this question hanging.
TLDR: Long story short, no Core 2 Duo is officially supported, and that P4 as scrappy it is might be very close to the best official solution (apart from some Pentium D series CPUs mentioned later). Generally no one should bother to try otherwise, don't even read any further, unless you are really interested.Now if you are really interested, please proceed further
Short story long an upgrade is possible, but it will take you to hell and back...
I've only registered here because I do collect old computers in my free time, and upgrade them with cheap old hardware (if possible) to give them away for charity. Recently I could have laid my hands on a piece of this type of machine and did some research on the CPU upgrade topic. I'll post what I find so it may probably be useful for other people.
Frankly I'm quite surprised that no official support personnel reached out to clarify this, since it basically would have been zero effort for them. If you know what to look for you can also easly verify this by looking at the available official BIOS updates, which mention all the CPU microcode updates in their description, and C2D is not among them. This is the description of the latest BIOS update and features the full change log:
https://support.ts.fujitsu.com/IndexDow ... 7A82340D68One interesting thing is, that at some point the change log mentions added support for BO, B1, C1 stepping, which hints, that Pentium D CPUs with these might be supported. Further along I mention D820 as a listed and supported CPU, and based on this I think Pentium D CPUs with the correct steppings and up to 95W TDP might actually work in this board. There are some CPUs in these series that do come with 130W TDP, but I have no idea about those. (Also the top of the D 9xx line offers comparable performance to the C2Ds in question, which might save you a lot less work for best possible performance, assuming that no later Core 2 [Duo or Quad] CPU might used by performing some magic described later.)
You may check this for yourself here:
https://en.wikipedia.org/wiki/List_of_I ... processorsAs for the product spec sheet goes, this is the one I could find:
ftp://ftp.webcentral.hu/pc-max/PC/Fujit ... leiras.pdf(Now this actually lists Pentium up D820 support, which I think only became supported with a later BIOS update regarding B0 stepping I mentioned above, and might not have been supported out of the box. But nevertheless that is the best officially supported CPU I could find written proof of.)
Now you would think that the socket of the mobo is actually physically compatible with the C2D socket (LGA775), so an unofficial BIOS mod could actually do the trick. Well yes and no, and it still won't work properly, but its discussed at great length here:
https://www.bios-mods.com/forum/Thread- ... 00-SupportIf you would like you can skip to the link at the end of the discussion which would take you to a page, where a guy went on the ultimate adventure beyond BIOS mods and physically tweaked things to work:
http://www.karosium.com/2012/02/fujitsu ... -hack.html
Now TLDR2 is, that you might have to flash a BIOS from a different board, then do some pin modding on the CPU and finally do physical modification to the motherboard. All this without bricking and breaking it. Now I would say that its totally not worth it for 99.99% of people. The rest 0.01% are enthusiasts anyway