iMac Screen Starting to Flicker with lines?

drunkmonkey

One of my iMac's screen is starting to flicker quite a lot, like when you phone or something like that starts to malfunction. The computer is working fine, i'm using it right now.
Any ideas what is gone wrong and any way I can cure it,
It's a 21.5 inch, late 2009, Nvidia Gforece 9400, 3.06 Ghz core due, it's about 2 and a half years old. It's been in the same place since new, never moved, dropped or anything like that.

Sad Professor

Take a screenshot - if the lines don't show in it, then it's probably the LCD.

This is how my 2007 iMac now looks:

drunkmonkey

It's not like that Professor, it's half the screen going blank, massive lines and the whole screen flickering violently. Like as if you kicked it or something.

I'll try and grab a screen shot but it happens so quick i'm not sure i'll be able to.

Sad Professor

It might be the backlight.

drunkmonkey

Found a video on you tube doing the exact same as what i'm seeing, only my screen is doing it on the opposite side, could that be a backlight, it comes and goes, it more or less behaved for the rest of the day after earlier on?

https://www.youtube.com/watch?v=Bis_JFxlFbY

ZENER

Almost definitely logic board. Not sure what version but some iMacs from that era were effected by the dreaded nVidia problem.

Ken

drunkmonkey

ZENER wrote: »

Almost definitely logic board. Not sure what version but some iMacs from that era were effected by the dreaded nVidia problem.

Ken

It's about 2 and a half years old, would it be covered if it's a known issue?

DubTony

ZENER wrote: »

Almost definitely logic board. Not sure what version but some iMacs from that era were effected by the dreaded nVidia problem.

Ken

The nVidia issue is on iMacs with a 7300GT graphics card (c. late 2006). I don't believe there's a known issue with later models.