Installing OSX via Target Disc Mode... help...

I have a 2008 20" iMac (silver) running Leopard. A couple days ago, the screen started acting funny. Now it's really, really bad - it makes these weird flickering "Atari-like", 80's-looking glitches all up and down the screen. Yellows, magentas, etc. And the computer can only be on for a minute until the mouse and screen stop responding altogether. Then I have to do a cold shut-down. It's completely unusable.

I ran Apple Hardware Test (both the basic and extended), and it claims there is nothing wrong. So I thought doing a fresh install of Leopard might fix it (even though it seems like it's a dying video card).

I can't get the iMac to do an OS install on its own. So I'm trying to use my MBP (running Mountain Lion) to install Leopard onto the iMac via Target Disk Mode. I can get the iMac hard drive to show up on my MBP desktop. Then I put the Leopard disc into the MBP. It click on the icon, click "Restart". It begins the "restart" but it never goes anywhere. I just get a solid gray screen.

Does this have something to do with the fact that the Leopard DVD is machine-specific? (It's the DVD that came with my iMac).

Help!

Yep, your MBP won't be able to install using a gray restore disk. You'd have to use either an identical machine or a retail version of OS X.

Stretch said:

Yep, your MBP won't be able to install using a gray restore disk. You'd have to use either an identical machine or a retail version of OS X.

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Is there any way these symptoms could be caused by a software issue? Or am I wasting my time trying to get a clean install on it?



I could always buy a retail disc, but I just checked on eBay, and it seems crazy to spend $50 on a 5-year old OS when I just paid $20 for Mountain Lion.

You can't boot the iMac Leopard DVD from your MBP because it is as you say machine specific for the iMac. It sounds like the hard drive in your iMac might be defective. Sometimes mechanical hardware errors will not show up with the Apple AHT.

Of course it could well be the GPU that's acting up. Either way, you may have to tear into the machine to do repairs. The GPU on your model iMac is soldered to the Logic board and can not be changed out without changing the entire board.

Stretch said:

The GPU on your model iMac is soldered to the Logic board and can not be changed out without changing the entire board.

Click to expand...

I could be wrong, but I think my iMac might not have the GPU soldered on. It's the 20" 2.66 Intel Core 2 Duo (early 2008). Is there any website out there that can tell you this kind of info for certain?

Would a bad hard drive cause funky graphics problems like this?

I could be wrong, but I think my iMac might not have the GPU soldered on. It's the 20" 2.66 Intel Core 2 Duo (early 2008). Is there any website out there that can tell you this kind of info for certain?

Click to expand...

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