iMac G5 and Fan Noise (my solution)
When I noticed the fan noise on my iMac G5 was becoming excessive, I started scanning the forums and there were many others with the same issue. Here's my experience with fan noise and how I solved the problem:
I have a 20" G5 iMac (second generation). I've owned it for about 9 months, and in the last month-or-so I started to notice a significant increase in the amount of "fan cycling." My kid plays Zoo Tycoon, which puts a heavy load on the processor and causes the fans to launch into the hoover effect after only a few minutes (sounds like a vaccum cleaner running). I also noticed that even under light CPU loads (Safari, Mail) I would hear significant noise coming from the fans - not the noise that comes from the spinning fan making physical contact with something (a mechanical problem), but rather the blowing noise that comes from a fan running at high speed.
Yesterday I decided to pull the back off to have a look inside. I didn't even have to turn the first screw to find the problem. The intake grating along the bottom was severely clogged with dust-bunnies. After a quick cleaning - plus using a can of compressed air to blow out the internals - the machine is whisper quiet again. It even keeps quiet under heavy loading, like hours of continuous Zoo Tycoon play.
Now I know this doesn't explain fan speed/noise problems for folks who just bought a new iMac, and many folks have fan issues that do require a service call to correct, but if you've had your iMac more than three months and you notice your fan cycling, even under moderate CPU loads, you may want to try cleaning it. If you're uncomfortable opening up the machine, just laying it on its back and vaccuming the intake grate will help. It's no secret that internal temperature regulation is very dependent on air flow, but it's the type of flow that matters. Low speed, high volume air flow is much more effective than high speed, low volume air flow at carrying away heat.
It's great to have my old iMac back. I'm going to a quarterly cleaning schedule whether it needs it or not.
Pete
iMac G5 Mac OS X (10.4.4)
I have a 20" G5 iMac (second generation). I've owned it for about 9 months, and in the last month-or-so I started to notice a significant increase in the amount of "fan cycling." My kid plays Zoo Tycoon, which puts a heavy load on the processor and causes the fans to launch into the hoover effect after only a few minutes (sounds like a vaccum cleaner running). I also noticed that even under light CPU loads (Safari, Mail) I would hear significant noise coming from the fans - not the noise that comes from the spinning fan making physical contact with something (a mechanical problem), but rather the blowing noise that comes from a fan running at high speed.
Yesterday I decided to pull the back off to have a look inside. I didn't even have to turn the first screw to find the problem. The intake grating along the bottom was severely clogged with dust-bunnies. After a quick cleaning - plus using a can of compressed air to blow out the internals - the machine is whisper quiet again. It even keeps quiet under heavy loading, like hours of continuous Zoo Tycoon play.
Now I know this doesn't explain fan speed/noise problems for folks who just bought a new iMac, and many folks have fan issues that do require a service call to correct, but if you've had your iMac more than three months and you notice your fan cycling, even under moderate CPU loads, you may want to try cleaning it. If you're uncomfortable opening up the machine, just laying it on its back and vaccuming the intake grate will help. It's no secret that internal temperature regulation is very dependent on air flow, but it's the type of flow that matters. Low speed, high volume air flow is much more effective than high speed, low volume air flow at carrying away heat.
It's great to have my old iMac back. I'm going to a quarterly cleaning schedule whether it needs it or not.
Pete
iMac G5 Mac OS X (10.4.4)
iMac G5, Mac OS X (10.4.4)
