I know this is not new, but after a year of sticking my generic probe into my reservoir, I noticed that readings have been rather high even when it is obviously not so.
That's a problem with generic resistance-based thermistors. After a while the sensor's performance degrades due to thermal degradation. Unlike Temp-to-voltage Resistance Temperature Detectors (RTDs) which are among the most precise temperature sensors commercially used. They are based on the positive temperature coefficient of electrical resistance.
RTDs are expensive though precise, and generally I believe most of the commercial temperature probes in PC temperature devices are thermistors, (due to small size, compact and inexpensive package and 2-wire probes, indicating thermistor-types), RTDs require 3-wire probes and a control circuit.
So with my generic temperature probe, I spent 3-minutes on this "project", cutting out the old probe, soldering a new female connector. And voila! I now have a probe that I can attach various after-market thermistor-based temperature probes and they all work fine! (Thermistors have no polarity).











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21 OCZ Fans!