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Mac Mini G4 turning off after 10 minutes


Well-known member
I replaced the HD on one of my rev. 1 Mac Mini G4s.
I put in an mSATA card with an IDE-adapter and set the jumper on it to slave. I have put mSATA cards into 2 previous Mas Mini G4s and these run well.

Now the fan is loud, it is continually on and it shuts down after 10 minutes. What was supposed to turn a quiet Mac into an even quieter, faster one has now given me a faster. louder Mac that it essentially useless.
I have altered the settings in the Energy Control Panel, to no avail.
I am using the MDD version of the Mac OS 9 Lives ISO as downloaded from the Macintosh Garden last year.

Was I too clumsy in the replacement and have damaged it?
Is it just bad luck on account of capacitors, as this iFixit article suggests [1]?
Is this a known problem and is there a known fix?
Would someone who understands what is going kindly explain to me what actually is happening?

I appreciate your help.

[1] https://www.ifixit.com/Answers/View/763162/Why+is+my+Mac+Mini+turning+off+automatically


Well-known member
First thing that comes to mind, concerns the fan itself. Some have reported similar surprising behavior previously when they removed the fan for cleaning and then re-installed it upside down. Any chance of that here? I’d check that first, unless the fan was not removed and re-positioned.

Secondly, was the heatsink removed and new thermal paste used? Many avoid this step; deeming it too difficult to tackle. But check the fan operation first and whether or not the fan is actually blowing OUT-wards at the rear (and maybe even what the exhaust air temperature actually is after 5 minutes of runtime). For more on new pasting see: https://macos9lives.com/smforum/index.php?topic=6875.0

And lastly… is “slave” actually the correct setting? (Too lazy to check my own setups here, downstairs.) But here’s a bit more on heat, mSata adapters, etc. http://macos9lives.com/smforum/index.php?topic=5955.msg52638#msg52638


Well-known member
Here's a question: could you have inadvertently damaged or disconnected one of the thermal sensors during disassembly/reassembly? I did that once in my old 2010 iMac which caused the thing to blow its fans like a hurricane. What I'd do is get an old copy of iStat Menus or the like, and check to make sure each thermal sensor is reading correctly, and not dropping out or reporting crazily high temperatures? I would think a detected thermal overload would cause the shut down.

Edit: I missed that you are using OS 9 on it instead of OS X. Is there an OS 9 utility to read the thermal sensors?


Well-known member
These are good points everyone. I can try install Mac OS X, if I can boot from an external FW drive and then check the heat sensors.
The fan is a very good point. I may very well have screwed it in the wrong way around. It would explain the constant fan and the machine turning off because it was simply getting too hot.
As for the slave setting, I can check on a Mac Mini G4 that I haven't yet opened up. I'm in the process of building a gaming LAN and that was gaming machine no. 2. Gaming machine no. 1 is done as is the server. I have 2 more that are still pristine that I can check.
Thanks for this.


Well-known member
I have good news.
I opened up a pristine Mac Mini G4 for comparison and noticed that the fan differed in rotation by 180°. The fan was otherwise in the right way. I also replaced the CW8124 with an UJ845 (giving the Mac Mini the ability to burn DVDs).
I turned the Mac Mini G4 on and it ran without problem. No continual fans. No turning off after 10 minutes. I don't understand what happened and if more info turns up, I'll update the thread.
Lessons learned from this is to take photos with my phone of the state of the thing that I am about to dissemble.

I should really check to see if the CW8124 CDRW drive is a possible cause.
I haven't installed Mac OS X 10.4 yet. Yesterday was a busy evening in the European Championship (soccer for those in the US). The hosts Germany got knocked out by Spain and the French just about knocked out Portugal, although, to be fair, I was hoping that both teams would lose. Switzerland is playing England. The former is on form and the latter have not really impressed so far. England, however, are perennial semi-finalists (and occasional finalists) and I have a sneaking feeling that they rise to the occasion this evening.
I still think that goalkeepers are the problem in football. They are too good at saving goals. Take them away and you suddenly get many more scores like 13-8 and fewer scores like 1-1. You get more goals, fewer penalty shoot-outs and far fewer draws.


Sounds like you just had the fan in backwards... but as an aside I'm curious why you installed the MDD image instead of the Mac mini image of Mac OS 9?


Well-known member
Sounds like you just had the fan in backwards... but as an aside I'm curious why you installed the MDD image instead of the Mac mini image of Mac OS 9?
It did, didn't it? And I was sure that that was the case.

Oh, and I got the name wrong above.
I'm getting MDD (Mirror'd Door Drive) with MTT (MikeTomTom — admin at macintoshgarden.org) mixed up.
It is MTT's version of the Mac Mini G4 SSW 9.2.2 installer [1] and I want to try it out and see if it is better.
I had & have used the MacOS9Lives v8 & v9 and have v9 on my file-server and it works more or less well.

[1] https://macintoshgarden.org/apps/mac-os-922-mac-mini-g4