All the core temps are bugged on every 1xxxTs CPU. They are anywhere from 16c off from idle to 5c off at full load.
Go by your CPU socket temp and ADD 3c for a good estimated Core temperature. Keep this number below 62c while overclocking and your voltage below 1.55v and it shall live a good 5 years
See where it says CPU? Thats your socket temp, so add +3c to that. So you are sitting at about 37c on your Cores. Not bad, but not great either, I am able to idle at 32~33c (adjusted temp) at 4.05 GHz @ 1.412 volts. I would very carefully monitor that temperature at full load (running Prime95 and complete a Small FFTs test for 15 minutes.)
You really need to see about getting the heatsink properly installed, I see you are 1.260v, that is almost 40c at idle, full load could really bring your temps up (and I don't mean just Prime95.)
Here is a comparison shot for you, but keep in mind I am overclocked, and almost 0.160 volts higher than you, so even though its only 4c here, at stock CPU speeds my temps maybe closer to 24c (20c ambient) which would make our difference by 10c. Even when I am stock, I am still 500 MHz higher than you.
You have a very capable heatsink and you could easily be idling at 28c. I don't want you to panic you or anything, just keep an eye on temps. I have seen similar situations and guys ended up running their processors at 65c daily thinking that was okay/normal and its really not (very bad temps (continuous) = very shortened CPU life.)
Edited by RagingCain - 12/23/10 at 9:38pm