I want to upgrade CPU in Dell optiplex 755 (SFF)

[patrykciach1]

I want to upgrade my CPU for intel core 2 processor t5800 and I'm not sure if motherboard is compatible with it

 

[william p]

http://en.community.dell.com/support-forums/desktop/f/3514/t/19502195
It lloks like 65nm Core2s with 1333 fsb support.
http://www.userbenchmark.com/System/Dell-OptiPlex-755/3939
I see Q9650 running here but they don't separate MT,DT or SFF computers.
Get the latest BIOS from Dell. They often don't update their CPU support list so hidden support in newer BIOS for unlisted CPUs is very common.