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elf69

macrumors 68020
Original poster
Jun 2, 2016
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Cornwall UK
OK so not all the time, only done it twice in a week.

My 2012 mac mini (server edition) has rebooted twice.
First off the primary screen goes black and secondary goes white. Then about 10 seconds later it reboots.

Once reboot it is fine.
Now both the drives in it test out fine. One 240GB SSD and a 250GB HDD.

These drives have come from my 2007 imac, this too would rarely freeze and have hold power button to reboot it.

Is there any other tests I can do on my SSD? If it is a drive issue I'd guess it's the SSD as it's the OS drive.

Any advice/input please.
 

elf69

macrumors 68020
Original poster
Jun 2, 2016
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Cornwall UK
Have two screen shots as two drives, seems my 2nd HDD not the SSD is failing.
Screen Shot 2018-10-12 at 14.44.24.png
Screen Shot 2018-10-12 at 14.44.35.png
 
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elf69

macrumors 68020
Original poster
Jun 2, 2016
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Cornwall UK
replaced the failing HDD and repasted the heat exchanger.

Still tripped out now and then.

So long term examination shows it overheating.
Problem seems be with fan control.

Minimum fan speed is 1800rpm, no matter what the temp it DOES NOT INCREASE.
gets to around 80 degrees then trips out.

Installed mac fan control and set it to 2500rpm constant and cpu diode remains around 45 degrees.

Is this a software or hardware fault?
 
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chrfr

macrumors G4
Jul 11, 2009
11,141
4,682
replaced the failing HDD and repasted the heat exchanger.

Still tripped out now and then.

So long term examination shows it overheating.
Problem seems be with fan control.

Minimum fan speed is 1800rpm, no matter what the temp it DOES NOT INCREASE.
gets to around 80 degrees then trips out.

Installed mac fan control and set it to 2500rpm constant and cpu diode remains around 45 degrees.

Is this a software or hardware fault?
Have you run the built-in hardware diagnostic? On a 2012 Mac, this would apply: https://support.apple.com/en-us/HT201257
 
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elf69

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Original poster
Jun 2, 2016
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Cornwall UK
Tried the diagnostic test....

Hold down D on boot and i get a white screen and nothing else!
Yes unplugged all but keyboard mouse and screen.

Duff mac mini maybe?
 
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RyanXM

macrumors 6502
Jul 7, 2012
480
499
DFW, TX
You need to perform an SMC reset. https://support.apple.com/en-us/HT201295

Also, your PRAM battery could be going bad or is bad. It will cause random issues as well. It is a BR2032, but you can use a CR2032.

I would also perform a PRAM reset. https://support.apple.com/en-us/HT204063
[doublepost=1549576055][/doublepost]
Tried the diagnostic test....

Hold down D on boot and i get a white screen and nothing else!
Yes unplugged all but keyboard mouse and screen.

Duff mac mini maybe?

Are you hardwired to the internet when performing this?
 
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elf69

macrumors 68020
Original poster
Jun 2, 2016
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Cornwall UK
I replaced CMOS coin cell when swapped the HDDs as yes flat.

Will do a PRAM reset.

was ethernet to router yes.
 
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elf69

macrumors 68020
Original poster
Jun 2, 2016
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Cornwall UK
No. I'm gonna pull both drives and do clean install on a NEW SSD and see how it goes.

Rule out both drives that way, as the SSD has been in 2 machines now without a clean install.
 
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jtara

macrumors 68000
Mar 23, 2009
1,989
530
Did you clean out the dust/dog hair/cat hair?

repasted the heat exchanger

Have you done this before? Do you know the correct technique? Your use of the word "pasted" makes me suspicious.

It's a common misconception that you should goop on a lot of heat sink compound. "More is better". The right way is quite the opposite. "More is better - not."

The compound actually has LESS thermal conductivity than the heat sink surface or the chip surface. The HOLY GRAIL of heat sink compound is to come up with one that is AS GOOD AS the heat sink/chip surfaces. This holy grail has not yet been achieved.

If you goop it on, you are doing more harm than good.

Spread it thinly, and then swipe with the edge of a credit card or other smooth edge. The purpose of the compound is to fill any gaps, uneven surfaces, pits, etc.

In a perfect world, the chip and heatsink surfaces would be perfectly planar, with no defects, and no heatsink compound would be used or necessary. But, alas, manufacturing is not perfect, and heatsink compound is used to provide a bit more thermal conductivity in places where the surfaces do not meet. The thermal compound is better than an air gap.

In the places where they DO meet, though, there should be NO compound.
 
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elf69

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Original poster
Jun 2, 2016
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Cornwall UK
yes very little used, I used to work for a pc repair shop.
yes too much holds heat.

yes cleaned all dust out etc.

But it seems "MRT" in activity monitor may be cause!
It's using 150-189% of CPU!

my CPU is sitting at 69-70 degrees C (according to Mac Fan Control 1.4.12) and keeps tripping out!

trying google what MRT is and how fix or disable it.
 
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chrfr

macrumors G4
Jul 11, 2009
11,141
4,682
yes very little used, I used to work for a pc repair shop.
yes too much holds heat.

yes cleaned all dust out etc.

But it seems "MRT" in activity monitor may be cause!
It's using 150-189% of CPU!

my CPU is sitting at 69-70 degrees C (according to Mac Fan Control 1.4.12) and keeps tripping out!

trying google what MRT is and how fix or disable it.
MRT is Apple's built in malware removal tool. You can't get rid of it but it's not normal that it'd use all that CPU time.
 
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elf69

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Original poster
Jun 2, 2016
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Cornwall UK
Gonna do fresh install on a NEW drive and see if it fixes all the issues.

It all points to software at moment and this drive been in two machines, just swapped drive no fresh install etc.

so I need start clean slate and go from there I think.
 
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elf69

macrumors 68020
Original poster
Jun 2, 2016
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Cornwall UK
OK I know old thread but it is mine and I have gotten around to doing stuff to this now...

So the 2010 mac mini server edition with 2x freshly formatted and tested HDDs.

First test was install old OS 10.7 (as temp misplaced my el capitan usb) This worked fine with now issues. Did not shut down, did not get that warm (40-55 degrees with mac fan control)

later found my high sierra usb drive. Installed high sierra ok but it started to run hotter right away.
Was running 55-68 degrees now. found a fan control app, not mac fan control though as that does not change with temp.

So swapped my SSD and HDD back in and installed the new fan speed app, it worked fine and did not shut down.

maybe an issue with my mini that newer versions of OSX cannot speed up the fans.
the fans remain at 1800rpm without a 3rd party fan speed app at ANY temp. Once hits 70 degrees the machine reboots.
It was stable for the 2 days I used it while I awaited an adaptor for my 2012 macbook pro to use an external screen.
 
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chrfr

macrumors G4
Jul 11, 2009
11,141
4,682
maybe an issue with my mini that newer versions of OSX cannot speed up the fans.
the fans remain at 1800rpm without a 3rd party fan speed app at ANY temp. Once hits 70 degrees the machine reboots.
It was stable for the 2 days I used it while I awaited an adaptor for my 2012 macbook pro to use an external screen.
Newer OSes work fine in the 2010 Mini and will adjust fan speed as required. Did you connect the thermal sensors for the disks? If those aren't connected properly you'll get erratic fan behavior.
Running diagnostics will let you know if the computer thinks it has a hardware problem.
 
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elf69

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Original poster
Jun 2, 2016
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Cornwall UK
yes reconnected sensors, used the ifixit guide to dismantle and put back together.
I'm not an engineer but worked for a computer sales/repair company for 13 years.

same issue with SSD or HDD fitted.
 
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