Only bootable in safe mode,damaged vsync cable
This iMac have a damaged vsync cable.
it can only boot up with safe mode, without safe mode it will always stuck at the apple logo after the chime or load up a cursor then became the beach ball. If it idle long enough in this state, the display will go to sleep.
When in safe mode, I can't run cinebench to test the gpu in safe mode. If I try to browse the web, Safari will flicker non stop, the video is just black colour. If I connect a external monitor and drag safari to the external display, I can view a flickering image of the video.
If I use safari in recovery mode, it flicker a lot lesser but stuck with beach ball and flickering stop.
Is this more like gpu issues or I just need to replace the vsync cable?
Is this a good question?