2011-2013 MBP 15 / 17 inch AMD 獨顯問題有救了！軟體回春術 (免費)

小弟這台MacBook Pro (17-inch, Early 2011) 硬體上同時擁有AMD Radeon HD 6750M外顯以及Intel HD Graphics 3000內顯，好一陣子因為會無緣無故死當及開機後出現紅色條狀閃屏，所以冰凍起來好久沒使用，最近想說把這台拉出來整理要換上SSD再重灌新版macOS，結果開機後狀況更糟，幾乎達到無法開機地步，機器自己會一直重新啟動就是進不了系統，開機按Command（⌘）+ R也進不去「macOS 工具程式」，偶爾會有一次幸運開進去系統，但是機器還是很不穩定，只要關機後重開又是一整個不行，完全開不了，機器很少用丟掉真的可惜。

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2018/09/28 更新解決方案總整理，適用於macOS 10.13.6 High Sierra版本，小弟自行調整測試過沒問題

To run your Mac on High Sierra 10.13.6, just follow below procedure step by step.
This tutorial is based on HFS+ (MacOS Extended Journaled) file system on MacBook Pro (17-inch, Early 2011). New APFS file system may not work on steps 4-17 so just go straight to 19.

(1) Use Time Machine or other tool to Back Up your Mac first
(2) Use macOS Recovery to freshly reinstall macOS : Hold down Command (⌘)-R immediately after pressing the power button to turn on your Mac, or immediately after your Mac begins to restart. (About macOS Recovery) (How to reinstall macOS from macOS Recovery)
(3) Select Disk Utility on the macOS Utilities window to erase the startup disk completely
(4) Select Reinstall macOS on the macOS Utilities window to Reinstall a new copy of Mac operating system
(5) The first time of Mac reboots when installation is complete, and then immediately go through the steps 1~21 below

1 - Enter macOS Recovery Mode (text mode or window mode)

Command (⌘) + R + S (text mode)

Then run the step 2 command csrutil disable, if you get the following error
『csrutil: failed to modify system integrity configuration. This tool needs to be executed from the Recovery OS.』, try macOS Recovery in window mode below

Command (⌘) + R (window mode)
It may take 5 mins to enter the macOS utilities window

2 - Disable SIP (SIP lock System folder -> no move kexts to another folder). SIP (csrutil) only enable / disable on Recovery Mode.

csrutil disable

3 - Restart the system

reboot

4 - Enter Single User mode 

boot up holding down the Command (⌘) + S keys

5 - Check a disk

fsck -fy 

6 - Mount a root filesystem with read/write permissions

mount -uw / 

7 - Make a directory to store the AMD drivers in case you'll need them in future

mkdir /AMD_Kexts/ 

8 - Move the AMD drivers

mv /System/Library/Extensions/AMDRadeonX*.kext /AMD_Kexts/ 

9 - Remove the AMD drivers cache

 rm -rf /System/Library/Caches/com.apple.kext.caches/ 

10 -  Just in case OS X will be dumb and will not recreate this directory, we are creating it for OS X

 mkdir /System/Library/Caches/com.apple.kext.caches/ 

11 - to update the timestamps so that new driver caches - without AMD drivers - will be definitely rebuilt

 touch /System/Library/Extensions/ 

12 - Unmount a partition to guarantee that your changes are flushed to it

umount /

* If the "unmount" command gives you an issue, like (umount(/) : Resource busy - - try ‘diskutil umount’ , just skip it and reboot *

13 – Reboot

 reboot

14 - Before enabling SIP again, try the normal boot without pressing any key. The Mac OS will rebuild the kernel cache and restart. See if the system starts normally. 

15 - Enable SIP again (restart the system)

16 - Enter macOS Recovery Mode (text mode or window mode)

Command (⌘) + R + S (text mode)

Then run the step 17 command csrutil enable, if you get the following error
『csrutil: failed to modify system integrity configuration. This tool needs to be executed from the Recovery OS.』, try macOS Recovery in window mode below

Command (⌘) + R (window mode)
It may take 5 mins to enter the macOS utilities window

17 - Enable SIP again

csrutil enable

18 - Restart the system

reboot

19 - Enter Single User mode 

boot up holding down the Command (⌘) + S keys

20 - type this in to clear GPU

 nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=

21 - Restart the system

shutdown -r now

Good Luck

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2018/01/08 更新解決方案總整理，適用於OS X 10.10 或更舊版本 以及 OS X 10.11-10.13 (El Captain-High Sierra)版本
這是原創網址https://shrib.com/#8hFKqOvvSNEYB2sK6-_9
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上網找解決方案，結果真讓我找到，而且是免費的喔！在這分享給有需要的人參考

這是原創網址 https://youtu.be/nFFPk3SeQbQ

解決方式是『利用軟件方式迫使Mac只用內顯，並防止Mac切換回問題外顯，還給你一個完美可再多用幾年的Macbook Pro！』

目前試過macOS Sierra正常運作，步驟 (步驟12可以忽略)，youtube上的影片內容應該是比Sierra更早的版本。

masOS Sierra版本，操作步驟如下：
1 - Enter Recovery Mode (text mode)
Command + R + S

2 - Disable SIP (SIP lock System folder -> no move kexts to another folder). SIP (csrutil) only enable / disable on Recovery Mode.
csrutil disable

3 - Restart the system
reboot

4 - Enter Single User mode
boot up holding down the CMD and S keys

5 - Check a disk
fsck -fy

6 - Mount a root filesystem with read/write permissions
mount -uw /

7 - Make a directory to store the AMD drivers in case you'll need them in future
sudo mkdir /AMD_Kexts/

8 - Move the AMD drivers
sudo mv /System/Library/Extensions/AMD*.* /AMD_Kexts/

9 - Remove the AMD drivers cache)
sudo rm -rf /System/Library/Caches/com.apple.kext.caches/

10 - Just in case OS X will be dumb and will not recreate this directory, we are creating it for OS X
sudo mkdir /System/Library/Caches/com.apple.kext.caches/

11 - to update the timestamps so that new driver caches - without AMD drivers - will be definitely rebuilt
sudo touch /System/Library/Extensions/

12 - Unmount a partition to guarantee that your changes are flushed to it
sudo umount / <- - - ***Try just skipping this step and restarting the machine***

13 – Reboot
sudo reboot

14 - Before enabling SIP again, try the normal boot without pressing any key. The Mac OS will rebuild the kernel cache and restart. See if the system starts normally.

15 - Enable SIP again (restart the system)

16 - Enter Recovery Mode (text mode)
Command + R + S

17 - Enable SIP again
csrutil enable

18 - Restart the system
reboot

19 - Open Terminal (Finder -> Applications -> Utilities -> Terminal (copy and paste) :
sudo nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=

20 - Restart the system
sudo shutdown -r now