Pixelated shadow on Imac 24" late 2006

[jvchawk]

Hello,

This is my first post in absolute to a Mac forum. I have been working for years with PC but last Saturday a friend of mine found an old Imac 24-inch late 2006 abandoned for years in his cellar and asked me to help throwing it away to free place. Well, I brought it home and saw that it powers up all right. The OS is 10.7.5.

What I found unsual is that there's kind of multi-coloured pixelated shadow around the icon shapes. I made a test with a print-screen shot of the Imac desktop. The file viewed on Imac is full of those shadows while the same file viewed on a PC is simply perfect. Of course not only the shown picture is full of those shadows but these shadows could be very well found also on desktop icons.

I made a research and found that due to hardware limitation, no OS X update can be done. I went through many various manipulations but the result remains the same. The positive point is that now I learnt some howto from Mac world: Boot Into Safe Mode, Run Disk Utility, Reset the PRAM/VRAM and SMC, Kill -KILL Dock. The only thing I'm still struggling after is to Run Apple Hardware Test as press "D" during start doesn't seem to do anything.

Does anyone of the Mac users of this community have a clue on this issue? Could it be a hardware related problem and in this case there's not a lot of things I can do I guess. Could it be just a software problem and there's someone in here who has already tackled it in the past and fixed it?

I here attached a few pics to establish the point.

Many thanks for your help to a novice.

 

[DeltaMac]

If the iMac has been sitting unused for some period of time, then you can try reseating the RAM in the slots. That MIGHT help the visual artifacts (or not) but is easy to try.
The graphics card is removable/replaceable, so you can also try reseating that graphics card. WAY more challenging than reseating the RAM sticks, as the graphics card is mounted on the back side of the logic board, and you have to pull that completely for that graphics card reseat.

The iMac is too old to have the built-in diagnostics test. You would usually run that by booting to the hardware test on the disk #2 of the original DVDs that shipped with the iMac. It's listed on the label of that disk.
However, the keyboard shortcut is the same, you just have to boot holding the D, while the grey DVD #2 is in the drive.
So, simple enough to run the hardware test, but that requires that you find that original DVD.

 

[jvchawk]

Thanks for the quick reply.

Went to Youtube and realised that the graphics card reseat operation is perhaps beyond my skill . So I started with the memory work by replacing the current 2 RAM bars with 2 brand new ones each 2GB DDR2 667. Then I reset the PRAM/VRAM SMC 3 times. The machine boots OK. The new memory is there. The problem remains.

I also tried to re-install the Lion OS X. During dowload operation, there was a message from app store saying that the download could not be completed because the article does no longer exist. I think it's normal because Lion is 4 generations old compared to the current and free El Capitan. On the other side, since my Apple Id is brand new, there's nothing like OS X 10.7.5 Lion in my purchased app store that I can download.

Thanks anyway!