In the course of creating the next Breen’s Bungalow (a QuickTime tutorial) for Macworld’s Virtual CD, I had occasion to disassemble an Intel Mac mini. After upgrading the mini’s RAM and mashing the machine back together I couldn’t help but notice that the computer’s fan ran constantly at high speed.
Turning to the Web, as I do when faced with similar predicaments, I found that this problem has cropped up for others—specifically some who visit Apple’s Discussions Forums. The advice for fixing the problems ran along the lines of unplugging the mini for a few hours and zapping the PRAM. Neither solved my problem.
One thread that seemed to be common to a lot of these complaints was the fact that the mini’s RAM had been upgraded. Could the solution lie in faulty RAM? To find out, I whipped out the putty knife to crack the case with the intention of pulling out the new RAM.
Part of the mini disassembly process involves unplugging a small black connector on the front of the mini. As I was about to do so I noticed that the connector was already unplugged. Apparently I hadn’t jammed it back into the slot as completely as I thought.

I plugged it in again, giving it a little extra push and reassembled the mini, hoping I’d stumbled upon the problem.
Indeed I had. The mini ran as quietly as it did when I first unpacked it.
This may not be the solution for everyone, but if your mini has been opened—either by you or someone you’ve hired—it’s worth considering.