Hi
Socket 775 to 1155 or 1150 does not fit
Apart from needing a new motherboard which will work with a Dell case ?
Check connectors for LEDs, power switch, front USB & sound in/ out on your Dell case are standard, as some Dells are decidedly non standard
Find out the fasted core 2 quad you board supports
Probably needs a bios update to support it (which can be risky)
Then look on eBay for a second hand CPU
You also need to see if faster CPU needs better heat sink & fan
(Again Dell usually non standard here as well.)
If new case , motherboard, psu , RAM, CPU use a retail CPU with std heat sink fan unless over clocking
Keep old gpu DVD , use old hard disk as a backup or second drive
Might as well buy a new base unit !
You are...