Imac 2009 Strange Screen glitch

[flibberflops]

I have just upgraded the GPU on an old imac 2009 27" and I am now getting some very slight vertical lines showing on the screen. They are spaced out about an inch apart and can be seen across the screen and seem to be moving. (see attached video link)

It DOESN'T happen on an external monitor, so I am guessing its some kind of screen fault?

Any idea's what could be causing it? Its a very difficult thing to google because any search of vertical lines takes you to the classic failed GPU threads.

 

[TwoH]

This is a defect with the LCD, and is pretty common on all 2009-2010 27” iMac LCDs. There isn’t really a fix for it other than replacing the LCD with a better one.