Yes, it's a straight forward swap.  Take proper precaution while working inside the machine, applying new thermal paste to the new CPU before reassemble the heatsink. With pricing not much different (only $1 - $2 more), why not getting an E5-2680 which has better performance than the E5-2665.
Hi All My system is running a Xeon Quad Core E5 1620 @ 3.6ghz. I understand I can install an Eight Core E5 2665 2.4ghz for a good speed boost, and they are available quite cheaply it seems. My BIOS is A18.  PSU is 425W. Is it a fairly easy straight swap to do this?  I can see there is already a MASSIVE cooling device on top of the CPU, which looks like a giant Heatsink.  I am hoping that would do the job for the faster CPU, and assume I would need a bit of heatsink compound when fitting it back onto the new CPU? Any advice appreciated
Advice Re Precision T3600 CPU Upgrade