how far have you overclocked it? i have my 8320 overclocked to a stable 4.5ghz with a h100i gtx liquid cooling setup and have never hit temps above 40*c..
even the stock cooler before i installed the liquid setup, overclocked to 4.4ghz only ever hit temps of 58*c, improper install of the heat sync maybe?
how long have you had this build? just wondering if its time to reapply thermal paste? regardless, id upgrade the cooler to at least the 212 evo/plus, if you have the extra money, and your case allows it, get the h100i gtx/h110i gtx
**any "casing" temperature reading should not read above 60*c, as 60+*c is the burn/fail temps for the 8320, induvidual "core" temps fluctuate and read a false temperature constantly; average from 3/5*c - upwards of 80/90*c
you can check your proper core "casing temp for the 8320 using AIDA64
http://www.aida64.com/downloadsalso.. if you could post a speccy s/s please?