Over Zealous iMac Fan

[EricNau]

First of all, I have two Rev. B iMacs (the ALS model). Both have similar configurations, but one's fans are MUCH louder. When computing at similar levels, one iMac will be a good 2,000 rpms ahead of the other.

While playing a movie in iTunes, I can hear the fans several rooms away (they are louder than the speakers, making it hard to hear). Meanwhile, my other iMac stays whisper quiet while playing the same movie.

I called AppleCare and the phone rep. heard the fans over the phone, so loud & clear, he told me not to power it on until the proper repairs had been made (he specifically mentioned it being a fire hazard).
So... I took it to my local AppleStore and the Genius said it was completely normal.

The fans themselves aren't any louder, they just run much faster for than normal.

It's interesting to note, with large differences in fan speed, both processors are close in temperature (+/- 8 degrees F), but the loud iMac's HDD will be a good 25-30 degrees lower. This leads me to believe the HDD fan may be the culprit. Note: Looking back on it, this probably isn't accurate.

I've experienced this problem for the life of the machine, but just now has it started getting really annoying.

Any thoughts? What should I do?

Thanks

 

[dopey220]

Uh... I'm not a big "computer guy," but you could just replace them. Then again, I'm sure it's a lot tougher with an iMac than it would be than, say, a Power Mac or a Mac Pro. Plus, I have absolutely no idea how much they cost. Probably not too much.

 

[Macmadant]

Reset the SMU, http://docs.info.apple.com/article.html?artnum=301733

 

[EricNau]

Uh... I'm not a big "computer guy," but you could just replace them. Then again, I'm sure it's a lot tougher with an iMac than it would be than, say, a Power Mac or a Mac Pro. Plus, I have absolutely no idea how much they cost. Probably not too much.

Actually, they would be very easy to replace, but there isn't any guarantee it will fix the problem. Also, it'll be hard to convince Apple to ship them out to me... they want me to take it in instead.

Reset the SMU, http://docs.info.apple.com/article.html?artnum=301733

I should have mentioned earlier, I've already tried resetting the SMU and NVRAM.

 

[extraextra]

I read the thread title and thought this was going to be a thread on a Mac fanboy/girl.

 

[EricNau]

Well I've found a rather simple solution to this problem (I'm not sure why I didn't think about it sooner). ...I just turned the processor performance down to "reduced." Now it sounds as quiet as it should be.

I'm not fond of having to keep my processor reduced for the rest of its life, but it's a small step to keep my sanity (and of course, I can always adjust the processor settings if I plan on doing processor intensive tasks ...and I'll just have to put up with the fans).

Another Note: This seems to have been a temporary fix. It seems to be just as loud as ever again (either that, or it's just become increasing annoying).

 

[iMacZealot]

As prompted, I will help you with this.

I have the Rev. 2 iMac G5. 17" Superdrive, 2.0 GHz. Originally came with only .5 GB of RAM, but I just bought a 1 GB stick and am trying to figure out how to put it in.

I can have as many apps open as I want to with the fan staying at a normal level if they aren't doing certain tasks. The worst is watching a YouTube video embedded on a website. It goes full blast. Any online video will do this, really. GarageBand goes full blast whenever I play something, and will oftentimes stop playing altogether. Final Cut Express is usually fine except for when rendering, when it goes full blast. It constantly drops frames whenever I watch a sequence, which really bothers me, but it's probably because of my insufficient RAM and because the video is being played from external FW400 disks. With iTunes, it will speed up, but not full blast. It oftentimes goes to full blast when I watch a DVD.

So, to conclude, as long as I'm not playing music, watching video, or playing a DVD, I can have pretty much as many apps open as I want. I'll see if my RAM upgrade will do anything for me.

Hope that helps.

 

[EricNau]

An update:

I've been to the genius bar regarding this issue two times since my original post. Both appointments have been with the same genius.

The first time I went in, after the diagnostics tests passed, she suggested I perform a complete Erase & Install to rule out any software related problems.

I did this and the problem persisted so I took it back a few weeks later. After listening to the machine for less than 10 minutes, she decided that there wasn't a problem after all, and that my machine is "perfectly normal."

Interesting notes: The genius suggested, if it really bothered me I could buy a new iMac, as they are much quieter (geez, thanks!). She also mentioned that I should have brought it in immediately after purchase for an exchange (but we all know that they only exchange broken computers). ...I'm confused - is my computer broken or not?

Meanwhile, it's still driving me crazy.

 

[EricNau]

As prompted, I will help you with this.

Thanks. Your help is much appreciated.

I have the Rev. 2 iMac G5. 17" Superdrive, 2.0 GHz. Originally came with only .5 GB of RAM, but I just bought a 1 GB stick and am trying to figure out how to put it in.

Interesting... this rules out the processor difference being the culprit (which was my suspicion after talking to the Genius).

I can have as many apps open as I want to with the fan staying at a normal level if they aren't doing certain tasks. The worst is watching a YouTube video embedded on a website. It goes full blast. Any online video will do this, really. GarageBand goes full blast whenever I play something, and will oftentimes stop playing altogether. Final Cut Express is usually fine except for when rendering, when it goes full blast. It constantly drops frames whenever I watch a sequence, which really bothers me, but it's probably because of my insufficient RAM and because the video is being played from external FW400 disks. With iTunes, it will speed up, but not full blast. It oftentimes goes to full blast when I watch a DVD.

So, to conclude, as long as I'm not playing music, watching video, or playing a DVD, I can have pretty much as many apps open as I want. I'll see if my RAM upgrade will do anything for me.

Hope that helps.

Do the fans quickly return to normal speeds after you quit the task? ...Once my computer gets hot it never seems to cool off (in some cases the fans will be running high nearly 30 minutes later). At other times an action as simple as navigating through folders can cause the fans to run full blast. Whenever I'm using that computer the fans are constantly revving up and down (that is if they aren't just running full blast).

On the other hand, I always have apps open on my other iMac and the fans are barely purring (I have to place my ear to the screen to hear them). ...And if they do run full blast (which is rare), within a minute of quitting the app the fans are back to normal.

 

[RRK]

Im not totally sure that Apple support works like this but it would make sense to me that you could call Apple and explain the situation and they could start the process from there. Get the work number and then take the computer to the Apple store give them the work number then they should be able to see the notes and instructions. It seems like you already suspect your genius is being either naive or deceitful with you so you have to go over her head.

 

[iMacZealot]

Do the fans quickly return to normal speeds after you quit the task? ...Once my computer gets hot it never seems to cool off (in some cases the fans will be running high nearly 30 minutes later). At other times an action as simple as navigating through folders can cause the fans to run full blast. Whenever I'm using that computer the fans are constantly revving up and down (that is if they aren't just running full blast).

On the other hand, I always have apps open on my other iMac and the fans are barely purring (I have to place my ear to the screen to hear them). ...And if they do run full blast (which is rare), within a minute of quitting the app the fans are back to normal.

They will return to normal whenever I quit that application or about 30 seconds after I stop playing video. I forgot to mention that simple tasks sometimes go full blast, like using the Finder. Also, sometimes, I'll leave it on and go do something else for about twenty minutes, and I'll come back and see it full blast and then some when it's not doing anything at all. Oh, and I don't think the processor performance selection does anything for you, either.

 

[EricNau]

An interesting observation: I just noticed that videos in iTunes are stuttering very bad (it's virtually impossible to watch any videos). ...These are videos that used to play perfectly fine on that computer, and still play perfectly fine on my other iMac (so it's definitely not a problem with the videos themselves).

Considering I've already performed a complete Erase & Install, and I was testing the videos after the computer had been under some strain just minutes before, I suspect it is heat related.


This is actually great news - I finally have actual symptoms!