Chaintech DigiDoc for zeinth 150 athlon 64 MB

Does anyone know the accuracy of the DigiDoc app for this MB? I'm
overclocking by about 15 steps in the bios & am getting a temp of 38c -
with my fan running around 3000rpm - this seems awfully low (got the
thermaltake volcano heatsink) - How does the DigiDoc read the cpu temp?
I didn't setup the thermal sensor that came with the heatsink - my
understanding was that i only needed it to run the fan's rpm in
auto-adjust mode.