Hi I have a dell optiplex 760 with lga775 socket set and I'm curious witch processor is the absolute best I can run the mothe

[Austin_68]

Dell optiplex 760 m863n

 

[clutchc]

Your best bet would be to use the service tag number on the dell support page to determine that. OEMs like Dell might use a proprietary motherboard/BIOS that will limit it to certain CPUs from that era.
http://www.dell.com/support/home/us/en/dhs?ST=dell%20support&dgc=ST&cid=297732&lid=5694052&acd=123098073120560&ven1=shq1FLOng&ven2=e&ven3=263803559254833622