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Hi My MacBook Pro seems to boot past the Apple icon and progress bar at startup but then the screen goes blue with black vertical strips. Booting in single user mode seems to say that it can’t read the hard disk but I have created an El Capitian bootable usb installer which has the same issue and have tried a different drive internally. I ran a full Apple Diagnostic but this didn’t find any issues. I have previously attempted to disable the AMD graphics card via Linux which was working fine. Please can someone suggest the cause of this issue? Thanks David
Sadly, your dedicated GPU has failed. Running the system under Target Disk Mode only uses the internal Intel CPU HD Graphics engine. There’s really nothing you can do to fix this all you can do is disable the dedicated AMD Radeon HD 6490M GPU. Keep in mind the HD Graphics engine is very limited in performance so you’ll need to limit your usage to low graphics types of apps (no gaming). Here’s how to disable it under MacOS dosdude1 - Disable MacBook Pro Dedicated GPU I would look at finding a 2012 MacBook Pro which has a better GPU sub system. Given the systems age, I recommend you do a full cleaning of the dust built-up as well as cleaning the old thermal paste off and applying a fresh coat.
Hi, this helps to me… Works for macOS Sierra and High Sierra (Improved version) Taken from StackExchange Thanks to LangLangC For temperature and other improvements see https://gist.github.com/cdleon/d16e7743e… This method leaves brightness control enabled Reset SMC Shutdown, unplug everything except power and hold leftShift + Ctrl + Option + Power I holded for 5 seconds, but holding just for an instant should work Reset NVRAM: Power up and hold Command + Option + p + r Until you hear the startup chime two times. Shutdown computer Power up and boot into Single User Recovery by holding if you are on high sierra 10.13.6+ you might need to use Command + r instead Command + r + s Disable SIP (This takes a bit to complete so wait for it) csrutil disable Disable Discrete GPU on boot by running nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00 Enable verbose boot mode (This will show text everytime you boot up, shutdown or restart your mac) nvram boot-args="-v" Reboot reboot Boot into Single User-mode by holding Command + s It might look as if it hanged, but press enter and you should see the shell (root#) Mount root partition writeable /sbin/mount -uw / Make a kext-backup directory mkdir -p /System/Library/Extensions-off Move ONLY ONE offending kext out of the way mv /System/Library/Extensions/AMDRadeonX3000.kext /System/Library/Extensions-off/ Inform the system to update its kextcache: touch /System/Library/Extensions/ Reboot reboot It will show a bunch of text in the screen (don’t be alarmed, let it finish) and then it will restart again In second restart it will show text in the screen again and then it will show normal login screen Your computer now should work properly (dGPU off and iGPU on, shown as i in gfxCardStatus BIG CAVEAT FOR APPLE UPDATES If an update that contains changes to the AMD drivers is about to take place it is advisable to move back the AMDRadeonX3000.kext to its default location before the update process. Otherwise the updater writes at least another kext of a different version to its default location or at worst you end up with an undefined state of partially non-matching drivers. After any system update the folder /System/Library/Extensions has to be checked for the offending kext. Its presence there will lead to e.g. a boot hang on Yosemite and Sierra, an overheating boot-loop in High Sierra.
