CPU compatibility/CPU upgrade, Dell Precision T7500

I am currently running a Dell Precision T7500 that has an E5520 2.27ghz quad core processor in it.  I've ventured into some light gaming with this machine and have decided to upgrade to make my machine more formidable at a budget.    First off I understand this machine nor xeon processors are designed for gaming and are not really ideal.   This is the cheapest and  best option for me in my situation I feel.  

I'm planning on upgrading to a X5680 3.3ghz hex core processor OR x5687 3.6 ghz quad core processer (my preference) and I've tried to research the compatibility of processor with my motherboard outside of the socket type (They match LGA1366 /  Socket B) but am not finding very much information to assure me that it is indeed compatible.   To my novice eyes it looks like it should work perfectly.

So I'm here seeking advice before proceeding to purchase this processor.   Thanks in advance for any help or tips!