I upgraded my sons abit an52 mothboard from a amd 4000 to amd 5200 (Brisbane).
With the 4000 all temps where fine, but with my 5200 I get idle temps off 52 to 56 celcius. When I read the temperature with everest I notice that cores 1&2 are much lower, 20 to 29 celcius but cpu temperature is reported 52 to 56 celcius, also in the bios. The cooler is correctly installed and fan working 100%, there is also an aditional fan in the case and there's a good airflow.
Your allusion to the codename of your CPU probably has everything to do with your problems. Google "brisbane" and "temp issues" and you'll find a wealth of information on faulty thermal diodes and whatnot. I'd be suspect of a temp like 20C because that's 68F and unless you have a turbine and extremely cold conditions in your house, it's unlikely that you can attain such a temp and maintain it during use. I used an app called SpeedFan to get the correct temps off my brisbane, which is free, just search and find it. I checked them with an infared temp gun. There's also a feature in CoreTemp to use an offset, which I never bothered with but just thought I'd mention it if you're using that app to get temps.
There's not a whole lot you can do about your issue short of installing your own temp probe, but good luck with that one..
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