MacBook Pro mid 2015 15 inch retina - flicker and flash!

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Hi folks -

I'd be very grateful for any suggestions you may have to help my ailing MBP please!

Mid 2015 15 inch retina, 2.2GHz i7 and all tickety-boo until a few days after upgrading to Mojave 10.14.2, I suddenly get blocks of random colour and flickering on the display. I power down, re-boot and run virus checks just in case (I spent too long with Windows!) and no problems detected.

Now, whenever I boot up, two thirds of the way through the process the display flashes various forms of this image

UNADJUSTEDNONRAW_thumb_13f3.jpg

and never gets to the log-in screen. Everything is absolutely fine if I boot in safe mode. I have tried resetting NVRAM and SMC and even inputting my password, but nothing works. The Apple Diagnostic says there are no issues found.

So I went to my local reseller, who said the logic board needs replacing. How can that be, if the diagnostic can't find a problem and safe mode is fine? Are there any home tests I can do to reassure myself the logic board does need replacing, before I shell out all that money?!
 
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Everything is absolutely fine if I boot in safe mode.
... ... ...
So I went to my local reseller, who said the logic board needs replacing.


Right off, I'd strongly suggest and say that your local reseller is an incompetent idiot and doesn't know what he's(she's) talking about!!!

Safe Boot disables most third-party software and that's why it's used for diagnosis purposes.

As an extra test, try setting up a new admin user and boot up and log into that new account and test.

Also, check your Users and Groups Pref Pane -> Login Items and delete any you might think might be causing the problem.





- Patrick
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Many thanks for the quick response Patrick.

The problem is, a regular boot never gets as far as the login screen. So sure, I can create another admin user and boot up fine in safe mode, but any time I try a regular boot the screen chops up before I get to choose the user to log in. I also tried automatic login, but that gets overridden if you previously logout, switch user or lock the screen.

I tried checking the Login Items - but there is not a single item listed in a safe boot - I guess that's normal. I understand Mojave creates a separate folder for these, but I don't know the path to see that folder if nothing shows up in the Users and groups pref pane.

Grateful for your thoughts!
 
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Have you tried using a monitor hooked up to it? It looks to me, as there is an issue with the GPU, so maybe an external monitor will be a way around that? But then it will just be a desktop.
 
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I think Bob has given you the solution. The GPU is very lightly used in Safe Mode, but a full boot puts it into high gear and that's when you get the broken patterns. And the only way to replace the GPU is to replace the logic board, as your local tech guy said. You can take the MBP into a true Apple store and they can run more detailed diagnostics on it than you can yourself. But I suspect if your local reseller is an authorized Apple reseller, he has run those same tests already.
 
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I think Bob has given you the solution. The GPU is very lightly used in Safe Mode, but a full boot puts it into high gear and that's when you get the broken patterns.


A good valid point, but wouldn't the video load be the same whether it was an internal display or external display that was connected???





- Patrick
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Yep. But as Bob has suggested, connecting an external monitor can eliminate any issue with the display panel itself and hone in on the GPU.
 
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Are there any home tests I can do to reassure myself the logic board does need replacing, before I shell out all that money?!


Think I would be inclined to create a new separate partition and install a brand-new OS in it and boot from that as a brand new user and see if things don't work a bit better.

If you get the same problem, I'll have to swallow Crow and apologize to insulting the dealer and possibly admit they were correct. But it's sure acting like a non-Apple software-caused problem.

But that maybe going to be pretty hard to do when you can't even boot the machine other than in Safe Boot Mode and I'm not sure If one come do an install when booted into safe mode. If not, then you may have to use Target Disk Mode and using another additional Mac.

PS: If you already have a compatible good working backup/clone on an external drive, try using it as a boot device and see if the problem disappears.






- Patrick
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pigoo3

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My immediate thought when I saw this was this MacBook Pro has a GPU issue...which would not be so great.

But I always like to rule out the possibility of a software/OS issue...and either test by booting from an external HD with a fresh OS install...or as Patrick suggests create a new account with a fresh OS install.

Fingers crossed it something simple,

- Nick
 
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Or do an internet recovery, or try booting from the recovery partition. Hold down Option while powering on and when the options appear, choose the recover partition as the boot. If there is no recovery partition, read this: https://support.apple.com/en-us/HT204904
 
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Thank you all for your replies!

Here's where I'm at:

1. Hooking up to an external monitor is fine in safe mode and gives the same choppy issues in normal boot. Did I say that the geometry flashes? Occasionally the screen goes black in the sequence and the cursor is then visible - and controllable - but the rest of the screen is black. Then the weird geometry reappears.

2. The local reseller is Apple authorized and is the only one in the locality. Any alternatives are a plane ride away, so I'm trying to diagnose a bit more myself, with your help.....

3. The machine starts fine in recovery mode, so I think I'm going to finish backing up, then try a Mojave reinstall.

One thing I still can't get straight: can there be a hardware problem if the Apple diagnostic (Power + D) says everything is OK?
 

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One thing I still can't get straight: can there be a hardware problem if the Apple diagnostic (Power + D) says everything is OK?

What you want to determine is if you have a hardware or software/OS issue. As suggested in the thread...a great way of doing this is by booting the computer normally from an external HD with a fresh OS install.

If you don't already have this at your disposal already...and with the MacBook Pro's current video issues...doing this may be difficult. If you have a 2nd Apple computer available to you & an external HD to use...that would be great.

The reason why you want to do this is...with a fresh OS install...you can eliminate any possible corruption, errors, or conflicting 3rd party app installs with the current OS install. If after testing with an external HD with a fresh OS install does not solve the issue...then the computer has a hardware issue (very likely a failing GPU)...graphics chip.

- Nick
 
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One thing I still can't get straight: can there be a hardware problem if the Apple diagnostic (Power + D) says everything is OK?


To be honest, at least in my Mac experiences, Apple's consumer supplied "Apple diagnostic" software is ~ let's just say, pretty basic to keep things polite.

But I would expect it to pick up a non-working GPU if it were goofy. And the fact that a safe boot seems to point to a software problem, I'd be looking at getting a pristine OS X installed even if it means a nuke&pave type install, which may be a bit of overkill at this stage.





- Patrick
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Thank you, Nick, for spelling things out and Patrick for your view on the Diagnostic: it all helps!

I'm going to have to figure out how to do the new OS X install over the next few days - I'll keep you posted.

I'm truly grateful for your expertise.
 

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I'm going to have to figure out how to do the new OS X install over the next few days - I'll keep you posted.

I'm truly grateful for your expertise.

Believe me...many of us totally understand how things can be being really far from an actual Apple Store to get face to face help. We've helped many many users over the years that were in just such a situation.

Having an Apple authorized store nearby can be helpful...but sometimes these folks may simply be an authorized dealer to sell Apple products...they may or may not be the greatest when it comes to solving technical issues.

If someone is more "on their own" as far as figuring out computer issues (with the help of Mac-Forums of course)...this sometimes means the person may need to have more tools & computer hardware nearby to help with the troubleshooting. In this case...having access to an external hard drive, a 2nd computer, and a way of creating a bootable OS installer will help lots with doing some troubleshooting...so we can figure out if we're dealing wth a software/OS issue...or a hardware issue.

Good luck...if you have any more questions or concerns...please post them.:)

-Nick
 
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I'm going to have to figure out how to do the new OS X install over the next few days - I'll keep you posted.


I would suggest if you haven't already done so, that the first thing you should do is to create a backup of your data assuming you want to keep it all.

After you have a current backup, then you can proceed with installing a new OS X.

I would suggest doing what I suggested in my post #8, then boot up using your Recovery HD and use the reinstall option to install into the new bare partition.

That should at least give you a pristine OS X to boot from and confirm the Mac is all working properly — or not.

If it doesn't, there are more serious problems to be dealt with.





- Patrick
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