Rich - My only concern is that the temperature range that those fan sensors range are outside our aquarium temperature. 85F inside of a computer case is VERY cool. 85F on our tank is very hot. So if you think about it, the fan may be running at low speed the whole time.
Update: I did a quick test of all the thermometer based on everyday stuff I had laying around the house. You can do the same thing to test your thermometer.
I put a bunch of crushed ice into a insulated mug. Poured in cold water. Put the mug inside a small Styrofoam box. Packed ice inside the box, surround the mug. Put the lid back on. Let the thing sit for 30 minutes to equilibrate. Open up the container, and pulled out most of the excess ice from the mug so that no ice (or very little ice) is actually touching the probes. . Put the three temperature probes (two corallife and the controller probe) inside of the mug. Put the lid back on. Let the thing sit for 30 minutes (to equilibrate again). Took reading. Open up the cooler to verify that there was still some ice in the mug. If there is no ice in the mug, your reading could be wrong.
Expected results: The temperature reading should be around 32F. Actually the temperature should be a fraction of degree lower because sublimination. If I really wanted to do this more correctly, I would have used RODI water and RODI ice.
Result:
Controller reported: 32F
First Coralife thermometer reported 29.8F
Second Coral life thermometer reported 32.5F
Conclusion: The controller was correct, and the Coralife (mentioned in the previous post) was incorrect.
I still need to get a lab grade thermometer.
Minh