After looking at some reviews for your heatsink I would say it's a little high, maybe try reseating the the heatsink again and make sure your only using a thin layer of thermal paste.
The same thing was mentioned
here and this solution worked for him.
Thanks for your input. I fourtunately fixed my issue however. I took my comp apart and reseated the mugen applying a much smaller amount of paste. This helps a small bit (2-3 degrees c). However the main issue was my voltage. I had done the "research" and tried to duplicate an overclock that was done on an 920 with C0 stepping. Come to realize mine has D0 stepping, so yeah less voltage was needed. I have it deadnuts stable at 3.8ghz with 1.24v and temps dont go above 62 degrees c even after hours of prime95.