6 Replies Latest reply: Nov 29, 2012 5:56 PM by CIAGP
CIAGP Level 1 Level 1

Frm iMac G5 1.8 GHZ 20" PPC.

This problem manifested after the power supply was replaced. Can anyone clue me in on the cause and repair colution? Thanks


imac screen photo.JPG

iMac, Mac OS X (10.5.8), 20" 1.8 GHz 2 GB RAM
  • Klaus1 Level 8 Level 8

    Can you describe 'video smearing' in more detail?

  • CIAGP Level 1 Level 1

    As the iMac finishes booting a few red/orange vertical lines appear rendomly. Then more appear in other colors all over the screen and within a minute or so the screen is covered (see image I included) and there is shifting of the lines as the mouse is moved around. Before it gets to this stage you can select menu items, but soon that becomes impossible and for all intent and purpose it's toast.


    Pretty sure it's the graphics card which if so this is an expensive repair and I just replaced the power supply and added more RAM. Sigh

  • Klaus1 Level 8 Level 8

    Your image does not show, but you may be right. Sorry to hear it.

  • CIAGP Level 1 Level 1

    Weird the image is not showing. I've inserted it here again:


    imac screen photo.JPG

    I ran it with the back off and it ran fine for about 30 min and then the verical lines reappear and with a few minutes the system locks up. Now more inclined to believe it's the thermal paste on the GPU that is failing as the 3 fans were running between 1500 and 1800 rpm, CPU temp was 126F, HD at 92F and the overall at 85F. No temp sensor on GPU so I would expect this is wher the heat issue is located. Not looking forward to dismanteling just to put new paste down.


    Anybody out in Mac Land tackled this reapplication or have any cautionary recommendations? Reapplying is not a big deal - it's getting to it and putting everything all back.

  • Rambling Joe Level 2 Level 2

    Either the Video Graphics card is going bad, or the capacitors are failing. If the capacitors look okay, it's the Graphics Card. Mine G5 ALS looked very similar to yours. Bad graphics card.




    Good luck,

  • CIAGP Level 1 Level 1

    I believe  the problem is either the caps or degraded thermal paste on the GPU. My friend can't find his Apple Hardware Test disk. If I had that I could probably figure out which.


    I have scoured the internet looking for a copy. Apple has some to download, but the one I think will work with this iMac seems messed up. Getting the downloaded dmg file converted over to ISO so it can be booted from a CD has been unsuccessful.


    Anyone out there in iMac Land havd a copy or have another link. It would be for an iMac G5 1.8 GHz without the ambiant light feature and no iSight, circa 2005.