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My Quad-Core Mac Pro tower is two days old. Initially, I was impressed with how quiet it was compared to my older Macbook Pro. Then on day two, for some reason it started running very loudly. It's not just a "little" loud- my wife walked into the room and asked what the noise was.

At first I thought this was just because I was hitting the CPU a bit (importing my iPhone library into iLife '09, and running Eclipse). But now that that's done, Activity Monitor shows a virtually idle CPU; there's nothing running that ought to be causing this, as far as I can tell.

I tried powering it off & letting it cool down for a few minutes to no avail; about 10 seconds after powering up, the box gets loud again. I took a look at it with the side cover off, and it seems to be the fan near the top middle, between the power supply and the disk drive.

It can't be a dust issue, as the machine is only 2 days old (and I peeked inside anyway just to be sure- clean). I did do a software update over the past 24 hours or so, but I can't say that it occurred immediately after that. I also did a migration of my old apps and data from my MBPro, for what it's worth.

  1. Why is it suddenly so loud?
  2. How can I monitor the fan speed and various system temperatures?

My temps and fan speeds:

enter image description here


Took it to the Apple Store. They took it in the back (where it's presumably quieter) and ran a fan diagnostic; no problems were found. The guy also told me that it was "a little loud", but normal. I don't buy it. It was virtually silent the first 24 hours I was using it. They would not replace/service it in the store (grrr... that's why I went there, as directed by Apple Care) but said I could get a replacement from the online store, as it was just purchased. I think I will try that.


Apple is letting me send it back for a replacement. Glad to see so many responses to this question mentioning that the MacPros are usually silent; it's not all just in my head.

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If its only two days old, have you thought about taking it back under warranty? Could be a faulty component. – Wayne Oct 29 '09 at 0:40
Hmm, I guess that's an option. But I doubt it's loud enough for them to consider it "broken". If I had turned it on and it sounded this way from the beginning I guess I'd have just accepted it, but it only started this after a day of near-silence. – Caffeine Coma Oct 29 '09 at 1:23
It doesn't only have to be the CPU - the GPU can also run pretty hot. – harrymc Oct 29 '09 at 7:03
harryc- true, but nothing interesting is happening video-wise. Not running a game, nor any fancy screen saver. Really just running Safari, and it does this 10 seconds in from a cold-boot. – Caffeine Coma Oct 29 '09 at 13:05
For reference the quad-core we have at work spins up when you start it up but by the time the Apple logo has come up it's whisper quiet. – Chealion Oct 29 '09 at 15:08
up vote 2 down vote accepted

I would image the drive and take it back. Sounds like a problem in the fan control hardware and/or firmware. I have a few MacPros at work and they are quiet. The hardware test you're already doing is also a good idea.

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Is there enough space behind it for air flow?

Is the case closed when it is powered on (it should be)?

Have you viewed "All Processes" and not just "My Processes" in activity monitor to make sure a processor isn't pegged?

Have you run Software Update to make sure you have the latest OS?

Have you run the Apple Hardware Test?

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The machine has a good 2-3 feet of space all around it. It's on a flat surface, no carpet. The case is on (only took it off momentarily to observe the fans). Airflow isn't an issue. Yes, I did "All Processes" in Activity Monitor. Yes, I did Software Update. I have not tried the Hardware Test, which I will do now. Thanks. – Caffeine Coma Oct 29 '09 at 13:04

It might be that the fan (or a bearing inside it) is broken, causing the extra noise?

Or perhaps the temperature sensor is faulty and things the CPU is much hotter than it actually is?

EDIT: Also, I've heard of faulty power supplies overheating the battery and laptop, might be worth checking too.

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It's a MacPro, i.e. the tower, not a Macbook Pro. – Caffeine Coma Oct 30 '09 at 12:24
Battery doesn't apply then, but faulty power supplies can still cause overheating :) – Jon Hadley Nov 1 '09 at 14:36

protected by nhinkle Apr 26 '11 at 23:28

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