imac 27" with horizontal line at startup

[katrienv]

I have a imac 27"
mid 2011

Had problems when starting, white screen and become very hot.

I opened the imac, it was full of dust. So cleaned it out completely.

After that I started the imac up without a problem.

The only one weird thing is that at startup I see the apple logo with the status bar and then for 2 seconds a horizontal line.

after that I can login and work with it, but I haven't seen this before.

Is it the graphics that is dying?

(a picture says more than 100 words )

 

[hsotnicam8002]

I have a imac 27"
mid 2011

Had problems when starting, white screen and become very hot.

I opened the imac, it was full of dust. So cleaned it out completely.

After that I started the imac up without a problem.

The only one weird thing is that at startup I see the apple logo with the status bar and then for 2 seconds a horizontal line.

after that I can login and work with it, but I haven't seen this before.

Is it the graphics that is dying?

(a picture says more than 100 words )View attachment 689152

[doublepost=1488208718][/doublepost]I have the same iMac with a similar problem. The Apple Hardware Test showed no problems. After attempting to start it over a 7 day period using various key combination I eventually managed to get to a an Apple internet recovery screen and erased the disk followed by a clean a stall of Sierra. It started normally. Then I opened Safari and YouTube. While playing a Youtube video the sound locked on and the computer locked. I restarted the iMac and I'm back to the white screen and can't get passed it with any startup key combinations. I can use CMD s. The only software on the iMac is that installed during the clean installation of Sierra. Any ideas?

 

[katrienv]

It's the graphics card. I watched also youtube video, white screen, not starting up now.

I changed the graphics card and up and running again.