I've been having problems with fan speed since I opened my Intel Mac Mini 1.66 GHz Intel Core Duo and installed more memory. In fact, it's open now.

I am running iStat Pro 4.5 and I see the following temperatures:
CPU A
CPU B
Ambient
Northbridge 1
Northbridge 2
HD

All temperatures look reasonable except for Ambient, which wanders around and can reach as high as 259 degrees F. I never see it really low; always higher than expected. The fan speed seems to track this behavior. I've checked all my connectors over and over and can see no issues. I noticed the fan speed connector is connected to a little PWB mounted on the corner of the DVD drive and appears to have a IR(?) sensor on it. Also, sometimes the Ambient temperature won't be displayed and only the other five can be seen.

The behavior makes me think I have a poor or cracked connection somewhere such that some high impedance point can hold a charge and thus a voltage. Because this PWB is very exposed, I am wondering if it can easily be damaged.

Also, there are four connectors similar to the fan speed connector in the rear of the computer near the audio jacks. I've had these off and on during disassembly. Do you or anyone else know the functions of these connectors?

Any help will be appreciated.

I Have a 2 * 2.66 GHz Dual Core Intel Zeon and installed iStat Pro 4.7 yesterday. Since then both CPUs are listed at 259•F and cpu and exhaust fans are on at maximum.

This doesn't seem healthy.