What is the best cpu this motherboard can handle?

[_Thomas_]

ftp://ftp.ts.fujitsu.com/pub/mainboard-oem-sales/products/mainboards/eol/eol_classicdesktop/datasheets/D2xxx/DS_D2811-A.pdf

I do know that the motherboard can handle 16GB of RAM so I also need a cpu that can handle that 16GB's of RAM.

(I'm doing this project for fun and I know building a new pc would be better for perfomance)

Thanks for the help

 

[CountMike]

Any 64bit processor can handle that much and even much, much, much more than that.
http://www.howtogeek.com/175443/what-is-the-maximum-amount-of-ram-you-could-theoretically-put-in-a-64-bit-computer/
It's up to MB and it's BIOS to determine RAM size limit. A 32bit OS can also address only about 3.5GB of RAM.
List of compatible processors is in that link of yours. Q9xxx, socket 775 are most capable processors in that list.