2016.2.12

**** problem

1월 하순에 잠자기에서 깨어나는 순간 screen freeze.

그 이후에 booting 시 애플 로고 이후에 white screen 이 유지될 뿐 진전되지 않음.

restoration from Time Machine and re-installation of Maverick, Yosemite, El Capitan are of no use.

If I hardware test with the system software CD, there is nothing.

safe mode booting is possible -> screen is a little stuttering: maybe hardware acceleration of graphics card is turned off

send the machine to Apple Service Center at JookJeon Emart with no final result:
Strangely enough, the technician said that even the safe mode booting was impossible and LED back light of the display was not turned on during booting, and hence he couldn't test anything. He suggest the graphics card is broken. But the iMac is so old that the graphics card is not available anymore. Kindly(?) he didn't charge the default service fee (44,000 won) since he couldn't find specific point of the problem.


**** solution

found a solution in internet:
When Mac OS X is starting, extension features are appended according to extension files in /System/Library/Extensions/

In safe mode booting, these extensions are not appended.

To be specific, ATIRadeonX2000.kext requires (maybe) the full power of the graphics card.

I removed the file from /System/Library/Extensions/ and now it is bootable.
(This removing is a little tricky for El Capitan. First, the System Integration Protection must be disabled and then later, enabled again. Reboot in recovery mode with Command-R. Open terminal and run an instruction "csrutil disable". Reboot in safe mode with Shift. Remove /System/Library/Extensions/ATIRadeonX2000.kext. Reboot in recovery mode with Command-R. Open terminal and run an instruction "csrutil enable".)

With Maverick, the stuttering is conspicuous, but the problem is mitigated with El Capitan.

Even video files can be played unless it is in full screen mode.

Note:
Keep watching the extension directory particularly after installing new applications.
After installation of some applications, the kext could be restored.


**** extra

The display is endurable but sometimes it is not.

I checked the second-hand price in Kmug.or.kr for this iMac. It is 550,000 won for a descent machine including keyboard and mouse. I guess there would be big discount for the faulty graphics card. Using this iMac as an external display would be much more beneficial.

I ordered Belkin mini displayport to mini displayport cable from Amazon to try Target Display Mode with Macbook Pro or Mac Mini.

I clean-installed El Capitan and installed applications as little as possible such as:
MacTeX, XQuartz, XCode, utorrent,
Java SE and EE, Apache Tomcat, Eclipse


**** ps. about VLC

I installed VLC to view some video files.
But it does not work and even worse, it installed ATIRadeonX2000.kext again.
I uninstalled VLC.