Graphics Glitch During Boot

Same issue in a 2011 MacBook Pro 15" , 2Ghz i7, 8GB ADATA RAM , with Intel HD Graphics 30000 (512MB), Crucial 240GB SSD. When updated to Sierra the digital "glitch" appeared followed by a solid black screen flash, then the system loads correctly but it's annoying. I'm downgrading to El Capitan...

Well On my 2009 I've upgraded to an SSD and see ZERO issues. In fact, it boots in about 20 seconds from power-up to desktop.

The only issue that I've noticed is the slight (super momentary) flick where the screen goes black at the first Apple Logo splash-screen when the progress bar is half-way across then the logo and bar reappears (a bit different) and then boots right to the desktop. The thing is though, oit has been doing that since well before Yosemite.

This post is specifically in regards to the Sierra boot glitch where you see a horizontal bar that appears across the boot screen roughly halfway through the boot process, then by a black screen, then by the system booting into the OS normally.

I've seen this issue arise on both desktop and laptops. Most recently it occurred on my Macbook Pro Early 2011. I was running Mavericks fine without issue. I then upgraded doing a format then clean install. The Sierra installer is coupled with SMC Firmware updates. After the firmware updates were installed the issue began happening.

Here is how to Fix (Cosmetically):

- Format

- Perform a Clean Install of El Capitan

- Download Sierra from within the App Store and begin the Sierra Install from within El Capitan

- After the install completes, Update as normal.

This should get you back into booting into Sierra without the Graphical Glitch.

*WHATEVER YOU DO, DO NOT PERFORM A PRAM RESET*

A PRAM reset will cause the issue to return. For whatever reason, performing a PRAM reset will cause the issue to appear.

I originally thought this was a hardware issue. So I took my macbook pro early 2011 to apple. They performed the graphics test on it to see if it was one of the faulty video cards that would be covered under the extension program. But the card passed. Additionally, my system was out of warranty. So I went and had both the integraded CPU/GPU and the discrete video chips properly reballed. This did not correct the issue, meaning it wasn't hardware related.

Hopefully apple will address this SMC / Firmware issue in an upcoming Sierra update. There have been reports of people who were experiencing the issue that the 10.12.3 update corrected the problem for them. But performing a PRAM reset brought the issue back. It doesn't affect system performance in anyway and is not related to any kind of hardware failure, it is purely software related.

Hope this helps others cosmetically fix the issue.

I had exactly the same problem on my 17 inch Macbook (late 2011), and I solved it by accident.

I decided to do a reinstall of Sierra and rebooted into recovery mode holding down cmd+r after the chime while the laptop booted up.

Went through the first few screens to reinstall osx and got as far as the Apple agreement, or possibly the screen after it I cant remember.

Realised Id forgotten to copy a file over, so hit the Apple logo to shut down and restart the laptop and backed out of the installation.

Rebooted and the glitch has gone.

Ive done about 20 restarts and shutdowns since and it hasnt come back.

No Idea what the technical reasons are, but it worked for me.

Hope this helps some of you.

I did more than just boot into recovery.

I booted into recovery, then clicked on reinstall mac os.

I then clicked on two or three links until I got to the Apple agreement page.

I cant remember whether I clicked on agree or not, but I then hit the Apple logo to abort the reinstall, and clicked on restart...........when my macbook rebooted into normal mode the glitch had gone. Two weeks later and it has not returned.

Hope this helps.

Im pretty sure it doesnt have any adverse effect either, as my macbook was running fine for months with the glitch, its just **** annoying. It actually started when I reset my PRAM while trying to solve the dead superdrive after os upgrade issue. Which I still havent managed to solve.

I have the same machine and GPU and OS, and I dont' see this, not even anything like this

can you try another monitor or dvi cable, or if you are using the mini to DVI take it out of the equation?

safe boot would disable the specific GPU driver and leave you with a working "video display"

your card could be at fault but you said you tried a 2nd card. Were they the same model card?

Same "problem" Link to a small flick: http://flyfishnorway.com/midlertidig_innhold/Oppstart%20MacPro%202010.mp4

Almost identical specs on MacPro

PS. Installed Sierra on a stocked HD, and the graphics glitch are gone. Maybe it´s my SSD causing the "glitch" ?