I replaced a Q6600 (2.4ghz socket 775) with a Xeon X5470 (3.33ghz socket 771) and the displayed temps were almost 15deg higher than actual. Looking around, I found this list of Tj Max values for various Intel CPUs:
https://forums.overclockers.co.uk/threads/official-tjmax-figures.17936945 (https://forums.overclockers.co.uk/threads/official-tjmax-figures.17936945)
X54xx was 85 deg and when I put that value into TThrottle's tjunction setting the displayed temperatures dropped to where they matched AIDA64 and SpeedFan.
There might be a better list somewhere else, but the change from 100 to 85 allowed all BOINC tasks on my MS-7380 motherboard to run at full speed.
HTH someone!