Random reboots iMac 2013?

[Truefan31]

I have a 27" 2013 iMac. Because it's a 1 tb spinning hd, I use a 512 gb crucial m100 ssd to a seagate external thunderbolt adapter for my boot drive. Been flawless the first almost two years now. Recently I've noticed it'll now randomly just reboot. I'll be in basically any program, or on the internet like safari or chrome. Sometimes I'll be on YouTube and it lets out a screeching noise until I manually hold the power button.

I did upgrade to El Capitan about 4-5 months ago. So I'm thinking that's when it started happening. I've read some basic troubleshooting. Maybe reset things like smc, pram, pmc? I haven't really started troubleshooting it yet. Maybe start by using the other tb port but now it'll run for a few days give or take between reboots. Ideas?

 

[VanNess]

I have a 27" 2013 iMac. Because it's a 1 tb spinning hd, I use a 512 gb crucial m100 ssd to a seagate external thunderbolt adapter for my boot drive. Been flawless the first almost two years now. Recently I've noticed it'll now randomly just reboot. I'll be in basically any program, or on the internet like safari or chrome. Sometimes I'll be on YouTube and it lets out a screeching noise until I manually hold the power button.

I did upgrade to El Capitan about 4-5 months ago. So I'm thinking that's when it started happening. I've read some basic troubleshooting. Maybe reset things like smc, pram, pmc? I haven't really started troubleshooting it yet. Maybe start by using the other tb port but now it'll run for a few days give or take between reboots. Ideas?

The random rebooting may be an issue with 10.11.4. I have the issue with my late 2015 27 Retina iMac and it began with 10.11.4. Completely stable with 10.11.3 and earlier. A couple of threads on the issue on Apple support forums here https://discussions.apple.com/thread/7512636?start=0&tstart=0 https://discussions.apple.com/thread/7520040

You can try to reset the SMC. Otherwise you can back to 10.11.3 via time machine backup or wait for a fix from Apple.

 

[Truefan31]

The random rebooting may be an issue with 10.11.4. I have the issue with my late 2015 27 Retina iMac and it began with 10.11.4. Completely stable with 10.11.3 and earlier. A couple of threads on the issue on Apple support forums here https://discussions.apple.com/thread/7512636?start=0&tstart=0 https://discussions.apple.com/thread/7520040

You can try to reset the SMC. Otherwise you can back to 10.11.3 via time machine backup or wait for a fix from Apple.

Yeah I did a diagnostic. No errors. Switched tb ports, we'll see I guess. Thought my ssd was going bad but I doubt it.

 

[Truefan31]

The random rebooting may be an issue with 10.11.4. I have the issue with my late 2015 27 Retina iMac and it began with 10.11.4. Completely stable with 10.11.3 and earlier. A couple of threads on the issue on Apple support forums here https://discussions.apple.com/thread/7512636?start=0&tstart=0 https://discussions.apple.com/thread/7520040

You can try to reset the SMC. Otherwise you can back to 10.11.3 via time machine backup or wait for a fix from Apple.

Well I did a smc and pram reset. Still having random reboots. The last time was while I was in boot camp.

 

[DeltaMac]

Your Boot Camp partition is on the internal (spinning) drive, correct?
I suspect your hard drive is starting to fail.

You mentioned that you have to force power off after hearing a screeching sound. That's what I would call your serious issue.
You should test the hard drive:
Boot to your recovery system, then run Disk Utility/First Aid to test the HDD.
If the HDD tests OK, you should also run the fans up to full speed with a fan control utility. smcFanControl is good for that.
You can change the speed of each fan individually. Run each up to full speed, then back down. Any mechanical problems should be apparent. There's not much more that will make a screeching noise - fans or spinning hard drive.

 

[Truefan31]

Oh ok. I did the Apple diag test it came back with nothing.

Yeah the boot camp is on the internal drive. My mac boot I use is on my ssd.

I need to try that. Gotta figure it out my apple care expires in November.

 

[Truefan31]

Your Boot Camp partition is on the internal (spinning) drive, correct?
I suspect your hard drive is starting to fail.

You mentioned that you have to force power off after hearing a screeching sound. That's what I would call your serious issue.
You should test the hard drive:
Boot to your recovery system, then run Disk Utility/First Aid to test the HDD.
If the HDD tests OK, you should also run the fans up to full speed with a fan control utility. smcFanControl is good for that.
You can change the speed of each fan individually. Run each up to full speed, then back down. Any mechanical problems should be apparent. There's not much more that will make a screeching noise - fans or spinning hard drive.

Yeah I can see maybe a hd issue its just weird that I'm having the issue on my Mac ssd boot drive and now on my boot camp. Maybe I'll try booting to my regular hd Mac (still on Mavericks) and see if it does it there.

 

[Truefan31]

I went into recovery. All drives were tested and verified as ok.

I'm gonna try I think booting into Mavericks and see if it does it

 

[h9826790]

If that happened in both OSX and Windows. Then it's more like hardware problem but nothing to do with 10.11.4.

Also, since both OS stored on different HDD / SSD. I will put them in the bottom of list for trouble shooting.

One of the most troublesome and hard to spot hardware failure is the RAM. You may boot from USB / CD and then run Memtest for a night. If nothing found. My next suspect will be the GPU. But anyway, do it one by one, test the RAM first. Without ECC, it's quite hard to confirm memory failure, which can cause all sorts of strange behaviour.

Or simply reseat the RAM, and use it for few more days to check if the problem still exist.

 

[Truefan31]

If that happened in both OSX and Windows. Then it's more like hardware problem but nothing to do with 10.11.4.

Also, since both OS stored on different HDD / SSD. I will put them in the bottom of list for trouble shooting.

One of the most troublesome and hard to spot hardware failure is the RAM. You may boot from USB / CD and then run Memtest for a night. If nothing found. My next suspect will be the GPU. But anyway, do it one by one, test the RAM first. Without ECC, it's quite hard to confirm memory failure, which can cause all sorts of strange behaviour.

Or simply reseat the RAM, and use it for few more days to check if the problem still exist.

well lately i've been booting into my regular mac internal drive which has mavericks on it. it's been 14 hours, no reboots yet. It's weird. Is it an el capitan issue? does that affect the bootcamp, which is on my internal drive as well?

I've reset the nvram and smc. You think it's the ram? It's got 24 gb, the checks so far have turned up nothing. I've read about using SMART utility. Is that a good tool?

 

[Truefan31]

Well so far so good, went two days with no reboots. Went back to my Mac ssd drive, still getting the random reboot. Smh

Thinking it's the software? Wish I could go back to Yosemite or Mavericks without losing my recent stuff.

 

[Truefan31]

I wonder if I try a fresh install of El Capitan will it work. I just did an update last time.

I just updated the firmware on my ssd. So let's see.

 

[Truefan31]

well i went to bed, woke up, and it looks like it's still rebooting. using some SMART tools it showed like 300 power interruptions. but i'm not sure if it's my thunderbolt adapter or the ssd. again this wasn't an issue when i had it on yosemite/mavericks.