Replace GPU after reballing

[Ubullmi]

Hello everyone,
I have an iMac classified as obsolete/vintage by Apple and so I had to fix it by myself. The problem was a frozen screen on the startup (grey window with the apple, vertical stripes and weird colours) that has been partially solved with a reballing on the graphic card (AMD Radeon HD 6750m 512Mb).

The problem, now, is that sometimes I see something like "undervoltage" of the screen (brightness reduces and then is restored, in less than a second, resulting in a sort of flashing).

Do you think that I can definitely solve this problem by replacing the graphic card with a new one?

Thanks in advance and sorry for my bad language.

 

[Nguyen Duc Hieu]

Hello everyone,
I have an iMac classified as obsolete/vintage by Apple and so I had to fix it by myself. The problem was a frozen screen on the startup (grey window with the apple, vertical stripes and weird colours) that has been partially solved with a reballing on the graphic card (AMD Radeon HD 6750m 512Mb).

The problem, now, is that sometimes I see something like "undervoltage" of the screen (brightness reduces and then is restored, in less than a second, resulting in a sort of flashing).

Do you think that I can definitely solve this problem by replacing the graphic card with a new one?

Thanks in advance and sorry for my bad language.

You can try replace the LCD backlight Power Board. The spare parts are cheap and can be very easily found.