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Late 2015 5k iMac fault

I

iJohnnyG

macrumors regular
Original poster
May 7, 2011
129
34
Newcastle
In March I purchased a late 2015 5k iMac for myself, mostly to replace my 2013 MacBook Pro.

Until around 3 weeks ago it worked perfectly, no complaints. I restarted the iMac one night, the screen appeared to go black but then a green screen appeared with black lines through the centre. The iMac restarted and thought nothing of it. iMac powered on, used it and then switched off.

The next day I switched on my iMac, used it and then powered off. The green screen appeared again. So I decided to do a fresh OS install. A couple of days had passed and after a couple of restarts, I was then greeted with a blue screen with purple lines. I then decided to contact Apple Support, followed their advice with the PRAM reset, SMC and fresh install. This didn't solve my issue so I took it into my local Apple Store (frustrating as I don't drive!).

In store they decided that the logic board had failed and needed replacing, so they did. After 6 days of waiting, I got the call to pick it up. The advised the logic board had been repaired, the iMac had been 'stress' tested and all was ok.

This afternoon I've just restarted my iMac and hello blue and purple screen. Any idea's what could be causing this if it's not the logic board? I'm so tired of having to complain to Apple, my 2013 MacBook Pro had it's logic board replaced twice.
 

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It's never got stuck on that screen, it has got stuck on powering up.
The colour screen only seems to appear when I power down or restart.
 
I have the exact same model as you. I have seen that screen as well on power up or down. Not every time, I don't think. I have not thought too much of it since the machine seems to be working fine. I normally leave my machine on 24/7 but I do restart a few times a week.

update: I have seen some odd colored screens on reboot a few times. It appeared more when I was playing tomb raider. I just did a couple restarts and no problem appeared, seemed normal.

I am not going to discern myself if I see an odd colored screen on power up or down if the machine seems totally normal after power up complete. Again I have seen a few odd screens on reboot here and their but never hung up on it or lasted more than a second. Never was performance an issue related to the reboot with that happening. Never has it done that during normal use only on a reboot.

On another machine I have, 2007 iMac C2D I had different screens appear on power up through out the years after updates or restores. It bothered me in the beginning to what made that change, it did not use to do that. That machine still functions the same as it did in 2007.
 
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Thanks for that, it's interesting to know that I'm not the only one experiencing the issue. Out of interest, how much ram do you have in yours?
I did a fresh OS install and experienced it almost instantly. I've contacted apple support again and am in contact with a rep there, hopefully a solution gets sorted soon.
 
I have a late 2015 5k iMac and have noticed this screen a few times when shutting down the Mac. M395, i7, 32GB RAM. It'd be interesting to know what's causing it...
 
mullock87 said:
I have a late 2015 5k iMac and have noticed this screen a few times when shutting down the Mac. M395, i7, 32GB RAM. It'd be interesting to know what's causing it...
Click to expand...
Same problem here, similar iMac 4GHz 16GB 512GB M395 2GB purchased in August-September 2016. Fresh installed macOS Sierra with full disk erase. Noticed the screen several times on power down.
My colleague with the same iMac stayed on El Capitan. When coming back from sleep his iMac completely freezes sometimes on log on screen to a point that even time in upper right corner freezes, only hard power down-up helps. Upgraded to Sierra recently, waiting to reproduce.
 
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iJohnnyG said:
Thanks for that, it's interesting to know that I'm not the only one experiencing the issue. Out of interest, how much ram do you have in yours?
I did a fresh OS install and experienced it almost instantly. I've contacted apple support again and am in contact with a rep there, hopefully a solution gets sorted soon.
Click to expand...

27-inch iMac 5K 3.3GHz, 32GB RAM OWC, 2TB FD, M395

I will be curious to what you find out. I have seen the screen many times, but I do not think I have seen it since the last OS upgrade Sierra. I have done a clean install 3 months back but that did not make a difference. I did the clean install for other reasons not the fancy colored screen ;)
 
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tryrtryrtryrt said:
Same problem here, similar iMac 4GHz 16GB 512GB M395 2GB purchased in August-September 2016. Fresh installed macOS Sierra with full disk erase. Noticed the screen several times on power down.
My colleague with the same iMac stayed on El Capitan. When coming back from sleep his iMac completely freezes sometimes on log on screen to a point that even time in upper right corner freezes, only hard power down-up helps. Upgraded to Sierra recently, waiting to reproduce.
Click to expand...

My Mac was purchased September and I updated to Sierra when I first used it. Hopefully the screen issue we all have will be fixed in a patch to the OS soon.
 
IngerMan said:
27-inch iMac 5K 3.3GHz, 32GB RAM OWC, 2TB FD, M395

I will be curious to what you find out. I have seen the screen many times, but I do not think I have seen it since the last OS upgrade for Siri. I have done a clean install 3 months back but that did not make a difference. I did the clean install for other reasons not the fancy colored screen ;)
Click to expand...

Ah so exactly the same as me then!
[doublepost=1478602887][/doublepost]Really interesting to see that other's are experiencing this problem. I've been in contact with an executive rep at Apple in Ireland, she's sending me back to the store so they can investigate further. Will keep you guys updated once I know more.
 
mullock87 said:
My Mac was purchased September and I updated to Sierra when I first used it. Hopefully the screen issue we all have will be fixed in a patch to the OS soon.
Click to expand...
Are you thinking its Sierra?

I'm on El Cap, as I've not upgraded, and I have a 2015 iMac (bought in November of 2015), i've not had any of those issues. I've read elsewhere some people were dealing with graphical anomalies with their MBPs because of Sierra.
 
Just thought I'd provide an update. Was asked to visit the 'lead genius' at my local store, he was running tests and my unit restarted through the test (it shouldn't), he then verified the screen issue when restarting and then after 30 minutes offered me a refund or a new unit. I took the new unit, set it up at home and restarted a few times, no problems.

Today I realised it needed to update (had to update to latest OS) and so restarted, issue appeared straight away. Surely this means it's a software fault rather than hardware?
 
OP wrote:
"Today I realised it needed to update (had to update to latest OS) and so restarted, issue appeared straight away. Surely this means it's a software fault rather than hardware?"

If you're getting the exact same problem as you saw before (on the old unit), I'd have to reckon that "the problem" is coming from software, not necessarily hardware.

My suggestion is that you revert back to the last older version of software that worked without problems, and "leave it be" for the time being.

I'd prefer older software that doesn't crash, to newer software that does...
 
I'm starting to see something similar on shutdown on occasion on my 5K (32GB of Apple RAM). Seems to have started once I swapped my 22" Acer for an HP 27" (both 1080p connected via DP to HDMI). The machine works perfectly and I game on it every day so I do not believe it's a hardware issue. Still have 2 years of AppleCare so not going to worry about it at the moment.
 
iJohnnyG said:
In March I purchased a late 2015 5k iMac for myself, mostly to replace my 2013 MacBook Pro.

Until around 3 weeks ago it worked perfectly, no complaints. I restarted the iMac one night, the screen appeared to go black but then a green screen appeared with black lines through the centre. The iMac restarted and thought nothing of it. iMac powered on, used it and then switched off.

The next day I switched on my iMac, used it and then powered off. The green screen appeared again. So I decided to do a fresh OS install. A couple of days had passed and after a couple of restarts, I was then greeted with a blue screen with purple lines. I then decided to contact Apple Support, followed their advice with the PRAM reset, SMC and fresh install. This didn't solve my issue so I took it into my local Apple Store (frustrating as I don't drive!).

In store they decided that the logic board had failed and needed replacing, so they did. After 6 days of waiting, I got the call to pick it up. The advised the logic board had been repaired, the iMac had been 'stress' tested and all was ok.

This afternoon I've just restarted my iMac and hello blue and purple screen. Any idea's what could be causing this if it's not the logic board? I'm so tired of having to complain to Apple, my 2013 MacBook Pro had it's logic board replaced twice.
Click to expand...
My 2015 5K iMac did the same thing. Apple replaced the logic board and it's been fine since.
 
i definitely think it's a sierra issue.
After receiving the 10.12.1 update i also have this garbled screen issue when waking from sleep. It's a very narrow portion at the top of the screen, not all of it...if i press any key on the keyboard, nothing happens..if i press the mouse button, the login screen appears..wtf.
 
zerozoneice said:
i definitely think it's a sierra issue.
After receiving the 10.12.1 update i also have this garbled screen issue when waking from sleep. It's a very narrow portion at the top of the screen, not all of it...if i press any key on the keyboard, nothing happens..if i press the mouse button, the login screen appears..wtf.
Click to expand...
This isn't actually the same problem OP is having, but I'm with you on the weird wake on sleep. I have deactivated my screen saver and haven't had the garbled top line but blank screen issue since, even after a day in sleep mode. Hopefully it actually fixed it and I haven't just gotten lucky the past week.

Edit: @zerozoneice after another one week I can confirm the issue no longer occurs. Definitely try deactivating your screen saver.
 
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iJohnnyG said:
Today I realised it needed to update (had to update to latest OS) and so restarted, issue appeared straight away. Surely this means it's a software fault rather than hardware?
Click to expand...
Downgrade and you have your answer.

I have read in other places about graphical issues, as I noted above. It certainly sounds like this issue is related to Sierra.
 
CWallace said:
I'm starting to see something similar on shutdown on occasion on my 5K (32GB of Apple RAM). Seems to have started once I swapped my 22" Acer for an HP 27" (both 1080p connected via DP to HDMI). The machine works perfectly and I game on it every day so I do not believe it's a hardware issue. Still have 2 years of AppleCare so not going to worry about it at the moment.
Click to expand...

So now I haven't see the issue for over a week. *shrugs*
 
This is an interesting thread. I have late 2015 iMac 3.2ghz with Fusion Drive. Like others, I've had some very odd anomalies on and off since I bought my computer in January this year.

Within forty-eight hours of buying my iMac, after rebooting my computer from cold, the display got stuck on a black screen, although the mouse was visible and moveable. I waited and waited but the desktop did not materialise. It freaked me out to the extent that I called Apple Support who ran me through Apple Diagnostics etc. which all came back fine. This issue has very occasionally reoccured and it has usually happened after shutting my computer down and restarting rather than rebooting. It's maybe happened four or five times.

I tend not to shut my computer down anyway, and just reboot a couple of times a week. I'm not sure of the wisdom in sleeping rather than shutting down, but I'd read somewhere ages ago that restarting from cold can needless tax the hard drive (this might be total nonsense, it is just that it made me nervous to shut down too often and it kind of stuck in my head).

It does seem strange that there are these rebooting/screen issues of different kinds on iMacs though... I wonder what the cause could be?
 
So after having my iMac replaced by apple, I can confirm that I've experienced the same issue. The issue must definitely be a sierra issue, it seems to happen less on this machine but it does still happen.
 
My 2014 imac was fine in El Cap, but when I got Sierra it too began going crazy (similar to OP but not identical) when I would plug my 4k monitor in, put the mac to sleep and then wake it. The main screen would go crazy for a few seconds similar to OP's, then it would just go black (on but black) and the 4k would just be solid green.

I ended up having to take the mac in for the screen to get repaired for other reasons so I reformatted it, then when I got it back I clone my macbook (still el cap) to the iMac and haven't had any problems.

I will not upgrade to Sierra again probably until it's a year old to give Apple some time to fix it.

Apple is becoming more and more like Microsoft in terms of having poor quality control every day.
 
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