The best thing to do whenever overclock an unfamiliar CPU with air/water cooling is what "Ibjamie92" said google around trial and error are your best friends. From my experience I am was able to get a 4.6GHZ.
I know some people who report things like 5.0GHZ and 5.2GHZ but it really depends on your setup and how comfortable temperatures you want your PC to run at.