temp reading software

[GJ02]

what the best to use ?
i have realtemp and coretemp
core temp is giving me a 6-8 degree higher reading than real temp, im confused.
im sure you need to get the right temp when monitoring so i dont want to screw this up

 

[GJ02]

so what should i do, change the lower temp or the higher temp ?
i need to know really the exact temp, im guessing change the lower to match the higher
whats a reasonable load temp for the E8500
with coretemp im idle @ 35 and 40 degrees