780, cpu upgrade

The 780 can take better processors.

http://i.dell.com/sites/doccontent/business/solutions/engineering-docs/en/Documents/optiplex-780-tech-guide.pdf

HOWEVER

This is one of the models that will never have any bios mitigations for Spectre Meltdown and Zombie Load. This means Bloomfield, Clarksfield, Gulftown, Harpertown Xeon C0 and E0, Jasper Forest, Penryn, SoFIA 3GR, Wolfdale and Yorkfield families and Xeon variants. Wont ever be fixed.

See  

https://www.amazon.com/Intel-Q9650-Processor-Socket-LGA775/dp/B001D86S3G/

Booooooo

https://www.grc.com/inspectre.htm

DELL™ OPTIPLEX™ 780
TECHNICAL GUIDEBOOK V2.0

NOTE: Processor numbers or MHZ are not a measure of performance.

Faster Front Side Bus and more cores may or may not improve performance.

MT DT SFF NOT for USFF
Intel® Core™ 2 Quad Q9650/3.00GHz, 12M, 1333FSB
Intel® Core™ 2 Quad Q9550/2.83GHz, 12M, 1333FSB
Intel® Core™ 2 Quad Q9400/2.66GHz, 6M, 1333FSB
Intel® Core™ 2 Quad Q8400/2.66GHz, 4M, 1333FSB
Intel® Core™ 2 Quad Q8300/2.50GHz, 4M, 1333FSB

Intel® Core™ 2 Duo E8600/3.33GHz, 6M, 1333FSB
Intel® Core™ 2 Duo E8500/3.16GHz, 6M, 1333FSB
Intel® Core™ 2 Duo E8400/3.0GHz, 6M, 1333FSB

780 what MT or uSFF? what case?

better to do what

99% of users do that and gain zero

why ask and not give one hint why, gaming dreams/

bitt-coin-mining dreams.

PCs can do 10,000 + things

name one thing that is not working well now with the current processor.

please , put the helper on same page, but if cash is cheap,

there are only 2 answers .

1 :dell supported processor clearly stated on the data sheet of you PC>

2: and what other have tried and seem to work ok. some even run fastest processor in the class GENERATION.

which answer do you wish?

its old cORE2 ,  only PC.

that is one limit there,

here is what MIGHT work, only you can try and do. on old PC no body upgrades this old

Q9650, 3 GHz, FSB 1333 MHz, L2 12 MB (that be the BIG GUN)

http://www.cpu-upgrade.com/mb-Intel_(chipsets)/Q45_Express.html

If your goal is gaming your money would be better spent on a newer model.

The 780 even with modest gpu can game.

https://www.youtube.com/watch?v=dLVrAW2Umk8

I would not recommend spending much for Ram or CPU.

Put any money into GPU specifically GT1030 GDDR5

https://www.dell.com/en-us/work/shop/pny-geforce-gt-1030-graphics-card-2-gb-gddr5-low-profile/apd/a9763687/graphic-video-cards