I follow a simple logic....no component in your system can go lower than the ambient temp (unless you are using liquid cooling
) So my guess is SYSTIN is probably your ambient temp (lowest reading)...now 45C does sound like a proper PCH temp coz I get PCH temp at 54C with about 35-36C ambient (India). I know that coz the BIOS clearly indicates the PCH temp. Cross check PCH from BIOS and HWiNFO64
-satyam