2008 iMac purple screen and lines

[JonCosman]

Anyone know how to fix this? I am installing El Capitan and have a purple screen with occasional lines. I thought maybe its the graphics card? Logic Board? Any hep much appreciated. I tried SMC and PRAM reset. Some times the screen goes grey at install then just stops and doesn't go any further.

Thanks in advance!!

 

[keysofanxiety]

Anyone know how to fix this? I am installing El Capitan and have a purple screen with occasional lines. I thought maybe its the graphics card? Logic Board? Any hep much appreciated. I tried SMC and PRAM reset. Some times the screen goes grey at install then just stops and doesn't go any further.

Thanks in advance!!

I'd put my money on graphics card being faulty. Whether you can get a used working one at a cheap price to make the repair economically viable is another matter. Some of the prices on eBay for the GPU are more expensive than a used 2008 iMac ...

 

[redheeler]

If your 2008 iMac is a 20", you do have to replace the logic board because the GPU is not separately removable. So I checked off everything except hard drive (although replacing it with an SSD would be a good idea).

 

[JonCosman]

Thanks guys I am pretty sure it is logic board. Before I make the final decision though I have heard if I replace the battery on the logic board it may fix purple screen issues. I also just tried swapping the HD and ram really quick with no result - Same purple screen and can only get into safe boot mode.
[doublepost=1465167947][/doublepost]Could anyone also confirm I need to get a whole new/used Logic Board, or can i get a new graphics card? When I open it up, it seems as though its all one piece. (Just guessing). Again Thanks for your replies!

 

[tedc99]

I have an early 2008 24" and had a similar problem 3 years ago which was the graphics card. I was able to get a new graphics card installed at the Apple Store for $183 (US), price includes new card and installation. Still going after 3 more years (8 years total for this iMac).

 

[stuartak]

Anyone know how to fix this? I am installing El Capitan and have a purple screen with occasional lines. I thought maybe its the graphics card? Logic Board? Any hep much appreciated. I tried SMC and PRAM reset. Some times the screen goes grey at install then just stops and doesn't go any further.

Thanks in advance!!

This may be a last resort but as your machine is old its unlikely to be cost effectively repairable , you could try "baking" the graphics (or logic board ) if not removable graphics card . look it up on Youtube , I have used this method on 4 Imacs of various vintage when all else failed and it worked on all of them , you will hear pundits saying you are "reflowing" the solder but I doubt that at the temps involved you are more likely doing something inside some of the IC's which whilst not a repair as such , has worked on all the machines I have done for at least 6 months , and as the alternative is the dumpster you have little to loose watch the video , you will need to remove the logic board to do this. Video is macbook but theory still holds.