Quote:
Originally Posted by PorPorMe  Gizmo!
With your background, I would think you could become a rich man with a program that works!  |
If I had a nickel.......
Actually, the problem you are seeing with inaccurate readings stems, I think, from the inherent inaccuracy of the sensors (or more correctly, the inherently inaccurate implementation of the sensors).
Mobo sensors are based on a 'band-gap' temperature sensor, which is implemented in one of two ways:
- A silicon NPN transistor has the base and collector tied together in what commonly called a 'diode connected' configuration, with the emitter grounded, and the collector tied to a voltage sensor.
- An actual diode is used, with the cathode grounded and the anode tied to a voltage sensor
A known reference current is then applied and the voltage drop across the temperature sensor is measured.
It turns out that the voltage drop across the band-gap in such a configuration is VERY predictable relative to temperature, ONCE THE DEVICE IS CALIBRATED. Calibration is the key. Typically, the sensor will be accurate to about +/- 5C (about +/- 9F), and how accurately it reflects the real temperature is a function of the temperature being measured.
However, if the device is calibrated (which involves applying two reference currents that differ by an order of magnitude, and then doing some complex math), you can get the accuracy of the device to about +/- 1/2 degree C (in some cases, even better than that).
The problem is, no mobo I know of is even CAPABLE of performing the calibration, much less actually doing it.
I've not personally verified this, but I've gathered that at least SOME BIOSes attempt to apply a SWAG offset to calibrate the diode based on behavioral data gathered from a production run. They will also attempt to SWAG the calibration based on the current temperature at the time POST runs, which means that the calibration can change between reboots, even if the temperature doesn't.
I've also heard (though I've not verified) that both Intel and AMD are actually calibrating their internal temp sensors on their latest CPUs, and that the calibration data are used to provide a more accurate temp reading of the
CPU temp sensor.