White Screen of death Booting problem...

[oldscribe]

Hi,

Have you run a AHT test?

If not have a look here to save a long post.

http://osxdaily.com/2016/06/25/how-to-use-apple-hardware-test-to-diagnose-mac-problems/

 

[THABARMAN]

Hi,

Have you run a AHT test?

If not have a look here to save a long post.

http://osxdaily.com/2016/06/25/how-to-use-apple-hardware-test-to-diagnose-mac-problems/

yes i have and it does nothing...

 

[oldscribe]

Hi,

Re read your first post and from your sierras number I feel your Mac is a March 2009 model, correct me if wrong. But if so it seems may well be the graphics card as 27" late 2009 iMacs seem to have a problem with this have a look here i know its an old thread.

https://discussions.apple.com/thread/5149001