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Noisy fan on Eight Core - how to pinpoint?

H

hungry ghost

macrumors member
Original poster
Jul 2, 2007
33
0
Hi, I'm experiencing very high/noisy fan on a Mac 3,1 2xQuad-Core Intel Xeon (2008). I've researched and I've taken the following steps:

• Blew out out dust generally from interior (mother board and fans without removing them)
• Removed video card (ATI radeon HD 2600) and checked the intake; blew out dust
• Removed RAM riser cards and blew out dust

This lead to a quiet mac at start-up, which made me think it might be the video card dust build up as I've read elsewhere (although there wasn't that much dust on it). But 3-5 mins later the fan kicked in again very loud.

Installed istatpro - 3 fans all running between 500-600rpm (the hard drive fan is running a bit faster at 800rpm). Temps all between 20ºC-29ºC with only browser running. Does this sound about ok?

I haven't installed any new OS on it. Does any one have any ideas on how to narrow the problem down?

Thanks in advance!
 
Have you run SMC updates? Your fan might be dying as well. Even though iStat says it's running at a certain speed, it could be rubbing up against something, or be damaged or dying in some other way. Are you able to pinpoint which fan it is that is loud?
-N
 
Is it noisy because it is spinning up or noisy because it is wearing out?

If the latter, you could dismantle the fan, oil/lubricate the bearing and put it back together again. I did that to one of my MacBook Pro's fans because it was faintly squealing.
 
I open the case while it's running, and stop each fan.

Press a finger against the hub of the fan, and it will stop spinning. (If it's behind a grille - use the eraser end of a pencil.)
 
Thanks for the replies. Some new info... I had done the SMC reset (unplug and plug back in again).

I'm 95% sure it's the Radeon video card fan making the noise: just diagnostics by ear with the case open.

Took it out, cleaned it with the blower again and checked the heat sink. (There was MINIMAL dust still at the end of the channels nearest the fan). Startup... again - 3 mins or so of quiet and then the fan kicks up again. Can't see any other obstructions and it seems to turn freely when spun by hand, so maybe it's on its last legs? I don't really fancy taking apart the video card!

Also, strangely the audio out socket is lit up red but I don't know what this indicates or if it is related somehow?

:confused:
 
hungry ghost said:
Thanks for the replies. Some new info... I had done the SMC reset (unplug and plug back in again).

I'm 95% sure it's the Radeon video card fan making the noise: just diagnostics by ear with the case open.
Click to expand...

As posted above, just stop the video card fan with your finger when the computer is running. You won't damage anything if you just stop it briefly.
 
Sometimes the bearings go bad on the fans and the only thing you can do is replace it. Does it make a buzzing/rattling noise?
 
hungry ghost said:
Thanks for the replies. Some new info... I had done the SMC reset (unplug and plug back in again).

I'm 95% sure it's the Radeon video card fan making the noise: just diagnostics by ear with the case open.

Took it out, cleaned it with the blower again and checked the heat sink. (There was MINIMAL dust still at the end of the channels nearest the fan). Startup... again - 3 mins or so of quiet and then the fan kicks up again. Can't see any other obstructions and it seems to turn freely when spun by hand, so maybe it's on its last legs? I don't really fancy taking apart the video card!

Also, strangely the audio out socket is lit up red but I don't know what this indicates or if it is related somehow?

:confused:
Click to expand...

TOS optical audio has a red LED for transmitting the signal - normal if it's optical audio out.
 
chrfr - yup, it's definitely that! Stopped it with my finger - noise gone.

Demigod Mac - no buzzing or rattling, it seems to spin smoothly - and you can actually see it spinning quietly for a few minutes at startup, before something kicks in and it goes into overdrive.

AidenShaw - thanks, that's good to know.

I guess at this stage I wonder if there's anything left to consider in terms of settings, otherwise I'll try and get hold of another video card and see if that resolves the problem. Unfortunately I don't have the original hardware discs, is there maybe some other 3rd party software that might give more diagnostics?
 
hungry ghost said:
I guess at this stage I wonder if there's anything left to consider in terms of settings, otherwise I'll try and get hold of another video card and see if that resolves the problem. Unfortunately I don't have the original hardware discs, is there maybe some other 3rd party software that might give more diagnostics?
Click to expand...

What version of OS X are you running? If you've upgraded OS X through the App Store, you can use the OS X update installer and create USB stick or DVD and boot from that to get to Apple's diagnostics.

Worth reading this too: http://support.apple.com/kb/ht1509
 
Did you use compressed canned air when you "blew out" the dust?
Take a small paint brush, dip the tip in high speed wheel bearing grease and lube the gap between the blade section and that lower section.
 
Last edited:
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