I recently built a system with an Athlon II x 3 450 with a coolermaster after market cooler (not the 212). It unlocked fine and now shows as a Phenom II x 4 B50 with the full 6 MB L3 cache. Lucky me. My question is why can I only get CPU temp in BIOs? AMD overdrive - nothing, Coretemp - nothing. I have run the AMD overdrive stability test no issues and Prime95 for 1 hour no problems but I am afraid to run it any longer with no way to monitor temps. Any help here would be appreciated. It is running like a champ and I would hate to bump it back down to 3 cores. I can see temps when it is listed as the 3 core CPU. The highest temps I have seen in BIOs right after Prime95 were 40 c and normally it is around 32 c which is on par with my Phenom II 955 BE in another machine. My guess is they lock down the 4th core because of this issue. Am I being overly cautious or should I just smile and move on down the road with my new Athlon now Phenom II and be happy I got it for $80.
Unlocking cores bonks temp readings so I wouldn't worry to much about not seeing them. Chances are they would not be accurate while unlocked. The best solution is drop it back to a triple core and compare your core temps to your CPU temp. This will give you a reference point when your unlocked and you can guess core temps off of your CPU temp.
I have found core temp readings on the 3 athlon x 3 builds I made are never accurate anyway (ie the PC im using reports them all 10C below room temp) do you get a CPU temp reading from the sensor on the motherboard? If so just use that.