I have a Biostar P4M900-M4, SpeedFan reads the temps as this:
IT8718 - (Pretty sure this is the CPU) - 28C on load with 400Mhz+ OC
ACPI - 16C (Temp Never Changes)
IT8718 (Don't know what this is maybe its the Northbrige temp) (Also stays at the temp neer changes) - 127C