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  1. #1
    Join Date
    Feb 2012
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    Default Mac Pro rear fan...

    No doubt this has been asked somewhere before but a search didn't throw anything up.

    I have a 2,1 Mac Pro, 3.0ghz and the rear fan is running flat out at around 2800RPM and sounding like a Ferrari in a tunnel!

    It's not software as the fans kick in almost immediately after the chime and do so on all disks I've booted from. None of the other fans are running above minimum and all temps are reporting normal - as you'd expect from a cold start.

    It would appear that it's going to be a logic board fault as everything I've tried does nothing to reduce the speed.

    I've put in Fan Control, SMCFanControl and SSD Fan control and none of them can affect the rear fan.
    As we all know, SMC only allows raising the min speed, SSD doesn't know the rear fan is there and FAn control doesn't work with 2007 or 2008 Mac Pros.

    So, apart from replacing the logic board - not going to happen on a 6 yo Mac Pro - is there anything else out there that I haven't found yet, or some command line instructions to bring it down?

    The Mac has/had 3 video cards installed and after I took out two of them there was a 20 second delay in the fan winding up, leaving me to think, for 20 seconds, that maybe the primary Nvidia card was the problem... except it wasn't.

    Any ideas on this one?
    The opposite of what you automatically assume to be the truth is the answer you're looking for!

  2. #2
    Join Date
    Feb 2001
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    on the landline, Mr. Smith
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    Default

    Hmm......try this one?

    Works nicely in boot camp for me.

    I wonder if it could be a bad/loose sensor somewhere? I think back to the early G5 iMacs, and (for example) there was a sensor on the HD. If one took the sensor off the HD, and left it hanging in the air......the sensor would not detect enough heat to kick the fan(s) up. Nice and quiet.....though you risk overheating the HD.

    But you get my point: If there is a bad sensor somewhere that is not part of the LB, you could consider relocating it. Any chance?
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  3. #3
    Join Date
    Mar 2001
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    Virginia... where one Democrat CAN make a difference
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    Default

    Have you tried resetting the NVRam can't hurt and costs nothing. the trouble is that I don't know how to do it. Search NV RAM here and it will come up. Or wait a few and someone will post the sequence. It's not hard as I remember I have just never had to do it
    Damien,

  4. #4
    Join Date
    Feb 2012
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    265

    Default

    Quote Originally Posted by Damien View Post
    Have you tried resetting the NVRam can't hurt and costs nothing. the trouble is that I don't know how to do it. Search NV RAM here and it will come up. Or wait a few and someone will post the sequence. It's not hard as I remember I have just never had to do it
    I thought resetting NVRAM died with Open Firmware and PPC Macs.
    The opposite of what you automatically assume to be the truth is the answer you're looking for!

  5. #5
    Join Date
    Feb 2012
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    265

    Default

    I wonder why that software didn't show up in the first 4 pages of a google search? Strange. Thanks again, that will be very very useful!
    The opposite of what you automatically assume to be the truth is the answer you're looking for!

  6. #6
    Join Date
    Feb 2001
    Location
    on the landline, Mr. Smith
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    Default

    Yeah......they sure need help with SEO, eh?

    I stumbled on it doing digging for something to help control fans (turn em up) in bootcamp mode for gaming. Apple does not spool up fans right in boot camp IMHO.

    After doing alot of digging to get past some crappy open source stuff, finally found this. Cool that they have both the Mac and Win versions, and you can crank fans up or down.

    A few others have used it with good success for Minis with a busted fan plug on the LB resulting in a fan stuck at full speed.

    Anyway.....spread the word. The software is a life saver.



    Oh, and I think Damien was referring to SMC/PMU reset. Worth a shot if you haven't done it.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  7. #7
    Join Date
    Feb 2012
    Posts
    265

    Default

    Quote Originally Posted by unclemac View Post
    Hmm......try this one?

    Works nicely in boot camp for me.

    I wonder if it could be a bad/loose sensor somewhere? I think back to the early G5 iMacs, and (for example) there was a sensor on the HD. If one took the sensor off the HD, and left it hanging in the air......the sensor would not detect enough heat to kick the fan(s) up. Nice and quiet.....though you risk overheating the HD.

    But you get my point: If there is a bad sensor somewhere that is not part of the LB, you could consider relocating it. Any chance?
    There aren't any sensors on the drives in the Pro as they're all on trays. No doubt they're using SMART for the internal sensors - but that is not a factor as the first thing I did was to pull out the internal drives and boot off my external testing drive. Same result.

    I take the point that any sensor malfunction would cause the default situation of fan running full tilt, but that wouldn't only kick in the rear (exhaust) fan as it would also, I expect, kick in the front fan as well to get the air moving.

    Nice one with the software! Works a treat - I've set it to run at 1000rpm, nice and quiet. I'll just monitor it for a while to make sure the temps don't rise as a result and client can have it back.

    Thank you.
    The opposite of what you automatically assume to be the truth is the answer you're looking for!

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