White screen

[danielef]

Hi guys,

my Imac 21.5 from 2011 showed a white screen all of a sudden, i had Lion installed.
tried the following :

- safe mode : starts but it shows a light blue screen and nothig more
- mac utilities : not starting
- internet recovery : it loads and shows minutes but after the minutes are over, white screen again
- boot from USB stick with Lion on it : it shows the USB external device in the boot loader menu , click on it, white screen again
- booting from his orginal DVD : DVD is ejected

I'm cluless....any idea?

Thanks in advance,

Daniele

 

[chscag]

Welcome to our forums.

Have you tried to boot to Recovery? Hold down command and r key as soon as you hear the boot chime. Keep holding until the Apple appears.

I suspect your DVD drive may be defective or dirty if it ejects your original DVD. The original DVD that came with the 2011 iMac was Snow Leopard. If you have a can of compressed air, you might try blowing air into the drive and then try again with the DVD.

It does sound like your hard drive in the iMac is defective, but try Recovery anyway. Let us know.

 

[danielef]

Hello! thanks for quick reply.
So when the HD is defective there is no way to boot either from DVD or USB stick ? i run the check disk via single user mode and no problem was found.
In addition to it , when i press command and R i get only the internet recovery.
I will blow some air in the DVD drive and i will try, i read also about FW upgrade for the disk (it seems to be a seagate barracuda), what about that ? sure it seems a blind option.

Daniele

 

[chscag]

It is also possible that the graphics in your iMac has failed. The 2011 21.5" iMacs used a separate graphics card which could be the cause of your white screen and failure to boot. Since your hard drive checks okay, the graphics card is a likely suspect.

If it is the graphics card that's bad, you may be better off buying a new machine. The cost to repair a 2011 model which is now 9 years old, may be more than the machine is worth.

 

[jasongoldworthy]

from what ive read here I think chscag is on to something

as the fact that your getting different colour screen's sounds like a bad GPU

this did happen a lot on 2011 iMac's ive had my fair share of them,

so trying to reinstall won't solve the problem hence why its hanging when its trying to load the software from the USB stick,

 

[danielef]

Thx guys, i think you're right and i'd better get over this.

 

[jasongoldworthy]

hi again


it can be temporary fixed but would require you to take the iMac apart and bake the GPU in the over at 200'c for 10 mins

remember to remove the heatsink and clean the thermal paste off first ofcourse

 

[jocarot]

This
I had this problem with and Imac 2009, and the bake works great.

hi again


it can be temporary fixed but would require you to take the iMac apart and bake the GPU in the over at 200'c for 10 mins

remember to remove the heatsink and clean the thermal paste off first ofcourse