I use an Aopen ax4b motherboard that has and still is serving me very well.
However, after a recent bout of spontaneous turning-off of the computer (it
turned out to be the PSU), I feel i nee to monitor my motherboard up front.
But the xp temperature monitors available all seem to misread CPU
temperature for this no-longer-supported board (70 instead of 40 as the
BIOS reading says). I can't seem to find a temperature monitor that
supports this board.

MotherBoard Monitor seems to allow a compensation setting. If I just put
this setting at -30 degrees is the calculation going to be accurate?