I have an older 2007 Mini (2GHz Intel Core 2 duo) that originally came with 1 gb RAM.
When I first got it I was surprised at how quiet it was. My previous computers all had fixed-speed fans, and the fans on the Mini seemed silent. They didn't seem to ramp up under even under load. I didn't even know they did ramp up.
As the HD got close to capacity, the mac slowed, of course. Trying to extend the life of it rather than buying a new one, I doubled the RAM and put in a 500 gb HD. (I did this myself.)
This sped the computer up, but I also noticed fan noise for the first time. All it takes for the fan to ramp up to a high pitched whine is scrolling in Safari. The fan speed does vary with temperature, and temperature varies with use.
It's so freaking loud that I moved it to under the desk because it annoys me so.
- Maybe the various upgrades and changes in web pages over time put more load on the processor, but I didn't notice it before the upgrade as the HDD and RAM limitations slowed the computer rather than taxing the processor.
- The fan ramped before, but physically it was much quieter than it is now (dust/bearings/wear problems).
- Mac overreacting to temperature.
- Incompatible hardware.
- Poor installation of some kind.
Here's a chart of temp vs fan speed (I just sampled some numbers while loading on the mac by opening tabs and scrolling):
Diagnostic things I've done:
- I checked to make sure the cables were reattached, I made sure the foam "T" was in the same place as before. Vents are not blocked, no buildup on fan.
- Did the reset thingie. (unplug, restart -- whatever the procedure was. I looked it up at the time.)
- I put the old HD and RAM back in. Still with the screaming.
- Did search after search. Other people who actually had this resoved hadn't connected the cables properly or got fixed with the reset. Others like me didn't get a resolution.