check the temp in bios... since you're relying on a thermistor, and the temp changes aren't registered very quickly, you can go from running prime95 and going into the bios and seeing what temp the cpu is at.
If your mb temp is in the 20s, and your CPU temp in the bios is in the 30s, this is a good indication that you're running an older unadjusted bios. If this is the case, i would check to make sure the heatsink is seated properly. Also, did you use heatsink grease, or the default pad(the default pad is better than a lot of greases).
Now, if your bios cpu temp is in the 40s, you likely have an adjusted one, so your temps are fine.
Mike