This morning I noticed that I couldn't hear my fan on my desktop computer. Opened it up, and fan is running on low. Never turns up. Downloaded a temp monitoring program. It says my CPA is 5 degrees C. This is not possible, as ambient temperature is 23 degrees. So, clearly the probe (wherever it is) is feeding bad info and so the computer is running the fan on low. Where is this sensor? Can I change it?