Xeon Processor Compatibility

Quick question:

I currently have this processor in one of our servers here at work:
http://processorfinder.intel.com/D [...] Spec=sl8p6

I want to add a second processor to give the server a nice boost since its the sql server and it working it ass off right now. I was wondering if this processor would work with the one above:
http://processorfinder.intel.com/D [...] Spec=SL8ZQ

I know they are ever so slightly different but will they work together without any system instabilities. The previous guy who managed the network before me didn't check on this stuff and had a very unstable server by using processors that were similar but not nearly as close as these two are. At any rate your help would be much appreciated.

Thanks.