It is a little confusing. I have the same board and have sensor 1
set to display board sensor Via686A-2 ( CPU ) and sensor 2 to display
board sensor Via686A-2 ( only way I can get it to read right ) and sensor 3 is set to VIA686A-3 ( that reads the case temp ) any other combination and I get something like a 225 reading on the cpu temp.
Now it reads 38C ( CPU ) and 30C ( case ) at load
Hope this helps
erg