MAC Mini: fan ran at full speed on power on - advice please

Am I correct in understanding from your posts that this mini has already been replaced once with another brand new mini? If so, was the power supply replaced, too?

If both are true, I suspect you have some power issue in your house.

Or possibly you are pulling the plug on your Mini while it is sleeping (not actually turned off) and that is confusing it.

But unless someone else has a magic fix, it looks like you'll be getting this one repaired under warranty.

Boece,

I really appreciate your attention and help. And will appreciate anybody else's thoughts. 'Cause I really gotta get this fixed.

A question though. Do you suppose it might help to re-install firmware and/or any firmware updates that have come along in the last year or so. (if any). I.e., maybe a firmware reinstall might help?

Welcome to Apple Discussions!

The experience you've had with your mini isn't a common one, but it has been reported from time to time, so it's not unheard of. I don't think there's been a clear reason found for this happening, and there is certainly not one from your description of this specific incident, but among the users I have who run Intel minis, I have had one where a boot failure occurred - the power light failed to light, though the chime was present and the system commenced startup then kernel panicked. An SMC reset was done and it has not happened again - though it may be purely coincidental that it hasn't happened again.

I would suggest that since you switched power off at the wall before rebooting, it would be wise to check you didn't inadvertently damage the drive's data structure or directories - not likely, but possible if the drive was attempting to write at the time, and then do an SMC reset. If you get any other similar events, post back, with as much detail as possible, including any odd behavior you may have experienced in the previous use, and what software you've installed.

To check the drive, run Disk Utility (in Applications>Utilities), then select the internal drive and firstly, click 'repair permissions', then once done, click 'verify disk'. Errors in the permissions will be repaired, though any in the process of verifying the disk would indicate the drive needs a repair which can be tried by booting the system to the original install disk (holding the C key down during startup) and running Disk Utility from there, this time clicking 'repair disk'.

To perform an SMC reset,
-From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
-Unplug all cables from the computer, including the power cord and any display cables.
-Wait at least 15 seconds.
-Plug the power cord back in, making sure the power button is not being pressed at the time.
-Then reconnect your keyboard and mouse to the computer.
-Press the power button on the back to start up your computer.

The reaction to power down is, as you say, a quite natural one in the face of the unexpected, and at least fortunately you have the benefit of a power switch at the wall, which is less likely to incur a voltage spike, than we do here, whereas here all we can do is pull the plug - which is rarely a good thing!

The fan on an Intel mini is designed to run at full speed in the event of an failure of the fan control line. Thus if there were an error state in the system management controller, the symptoms you describe are entirely possible - hence the suggestion to perform an SMC reset, since that would clear an error state unless there were a hardware fault. What doesn't entirely make sense is the lack of the power light, though in fact that may relate to the same SMC error since it too is controlled by the system management controller.

It's not likely that software installed could cause this, but it is a remote possibility, because there are occasions where the NVRAM gets corrupted and can cause bizarre mis-configuration and startup issues, and there are some instances where this is down to installation of non-compliant software. Very rare though.

There are a coupel of neat utilities to keep on hand if you don't have them already: Preferential Treatment which is extremely useful at finding property list file errors and allowing damaged ones to be removed from both system and user level, and YASU for performing a wide range of basic maintenance and trimming functions. Both can be downloaded from www.versiontracker.com. Neither can do much real harm if abused or overused, but neither needs to be run often - indeed, typically only if you are trying to troubleshoot or resolve odd problems. If you don't have these, I'd recommend you download them and have them handy just in case!

By the way, if you look at your reply and see a couple of words that have turned into hyperlinks for no apparent reason, it's an issue with the editor used in Apple Discussions and is due to be worked on this weekend - not something you did.

Hi, here is something to add to this discussion and any help would be most appreciated. I've owned a G4 Mini for a couple of years. No problem. I bought a core duo on September 1, 2007 and when I plugged it in right out of the box it wouldn't start up. I fiddled around with it and it finally booted up. Five days later I unplugged it and set it up in a new location. It wouldn't power up again and Apple told me to reset the PMU by holding down the power button while plugging it into the wall. It started up, but without any light on the front and with a really loud fan noise, and excessive heat. Apple said it probably was the logic board and the company I bought it from replaced it.

Now comes round two. The new Mini was fine out of the box. Yesterday, thirty days after I bought it, I had unplugged all my computers (a G4 Mini and a PC) because we were due for a stormy night. I unplugged them at the computer and not wall socket. This morning, all booted up just fine except the new Mini... it wouldn't boot up and when I reset the PMU the computer started... without any light on the front and with a really loud fan noise, and excessive heat. When I called Apple, they were stumped and again, said it was the logic board. This time the company I bought the computer from would not replace it and offered to get it fixed. (I will add that all my computers and peripherals are plugged into a surge protector.)

I did an Apple Hardware Test and the Disk Utility First Aid. Nothing showed up as a problem!

Now here is where it gets one thinking... could unplugging a computer or having the power go off, have an impact on the PMU on the Intel Minis? Does anyone have any solutions or help?

Many thanks, Sue

+Intel Mini ... Apple told me to reset the PMU by holding down the power button while plugging it into the wall.+

This was incorrect information: the Intel Mini has a SMC reset, rather than a PMU reset. And the difference is that you don't hold down the power button when reattaching the power cord.

The procedure you performed will cause the fan to run full blast on an Intel Mini. The cure is usually to do the SMC reset by not holding down the power button.

Thanks for the info. Apple actually told me both. One tech said to reset the PMU the other tech said to reset the SMC. When I do an SMC reset by unplugging everything including the keyboard and monitor, then the computer won't start. Nothing will make it start, unless I reset the PMU... then comes the fan noise and no light. I just tried resetting the SMC again and it is dead as a doornail.

Again, this seems to have something due to when the electricity goes off, or the computer is unplugged for more than a few seconds, the SMC and PMU become corrupt...? Is this just an odd case of the two I have gone through in a month?

Thanks, Sue

Couple points of clarification which probably won't help you, but will keep this conversation a bit saner:

1) There is no PMU on an Intel Mini. The comparable item is called a SMC. (And as explained above the procedure for resetting the SMC is not the same as that described for a PMU on a G4 Mini.)

2) Performing the "PMU procedure" on an Intel Mini will often cause the fan problem you described.

3) When plugging in the power to reset the SMC or the PMU, I'd recommend doing the final plugging at the Mini end, not the wall outlet end.

If your power is as problematic as you indicate, I'd recommend a high quality, high capacity UPS (Uninterruptible Power Supply) to protect your equipment. (Most plain surge protectors are virtually worthless.)

Many thanks for the post. Yes, I will look into a UPS. It is odd however that both minis share the same surge protector gadget (6 electrical, plus telephone). But the only thing I've had problems with is the Intel Mini.

Do you have any suggestions as to how I can get the Mini to power up after I do an SMC?

Thanks, Sue

Thanks for the reply. The mini was replaced by a brand new mini and the serial numbers were kind of close. When I unplugged the computers they were turned off and had been off for at least an hour. None of the other equipment like back up drives and the G4 mini which are also plugged into the surge protector have experienced any problem.

I have no wish to offend. But in general, when two new computers have the same unusual problem, the suspicion is that the cause is local-environment or user-error.

That is why I brought up power as a cause, and speculated about how the Minis might have been shut down/unplugged.

Of course it is also possible that there was a bad batch of Minis -- though that seems less likely to me than the "usual suspects".

Having said all that, it would probably help our troubleshooting to know exactly what is/was plugged into your Mini.

And it would also be good to know if your equipment is plugged into properly grounded (earthed) three-prong outlets. There are outlet testers available for about $5 at Walmart or hardware stores that can test for ground, reversed polarity, open neutral, etc. If the wiring in your house is old or has been recently modified, an outlet issue is possible.

Hi, no offense, and your response is most appreciated. I shut down my mini always by using the shut down on the Apple menu. All that is plugged in to the back of the mini is my monitor, keyboard and mouse.

I have another mini plugged into the same surge protector (G4) that has not had any problem in two years as well as some backup hard drives. Also, my house is new with new wiring. When both of these Minis experienced problems, it was AFTER they sat without a power cord attached (1 hour to 8 hours). My problem was, when the power cord was reattached to the back of the computers they would not boot up. Nothing could make them boot up except "resetting the PMU" which starts up the fan motor thing.

Again, this seems to revolve around letting the unit sit without power...?

Any other thoughts?

Thanks, Sue

Hello Sue,

What happened with this? I had the exact same thing happen with my Intel mini. I'm about to returm to MacMall with this new (replacement) one that has the same fan/light problem suddenly. Bought the first in early October. Did you buy from MacMall? What was the serial if so?

John

Hi,

This thread seems close, but not quite my problem.

I have 3 G4 PPC minis and have been inside each several times. On my last foray I installed a Hitachi E7K100 100GB 7200RPM drive into a 1.5 G4 miniMac.

Somewhere I goofed. Now, when I plug in the power cord, the fan comes on at high speed. The computer is otherwise off, no booting, no video, just the fan running at top speed. I can then press the power button and it boots and runs. ...and it runs very nicely, thank you, except for the fan noise. ...normal in all other respects. ...CPU temp 85F.

Nothing I've tried causes the fan to quiet down, including several PMU resets. I've gone back in to be sure everything is right but nothing seems awry. I even re-installed the original drive. Still full fan.

The G4 minis don't have a thermal sensor wire like the Intel minis, but I suspect my problem is related. Any suggestions as to the cause?

My thanks.