Do your CPU temperatures go down instead of up when you go from 0 load to 100%?
If that's the case, I think what's happening is you have a CPU that reports the difference between the current temperature and the Maximum allowed temperature, rather than the absolute temperature. Some of the newer chips do that. I've got a new laptop with a Core i3 that I think works like that. In any event, CoreTemp (or any other program) doesn't show a valid temperature on that laptop, but the BIOS is controlling the fans correctly.
Just because you're seeing funky numbers doesn't necessarily mean it's not working correctly -- but you might need to let the BIOS do all the fan speed controlling as the third party programs may not read the temperatures correctly.
EDIT: 23C sounds about right for a chip at full load that reports temperature that way. My C2Q reports temperatures the normal way, and the BIOS varies the fans to keep the temps around 20 degrees below the TJ Max temperature.
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