Interesting iMac issue

Recently got my hands on an iMac5,1 aka Core 2 Duo @ 2GHz EMC 2114. Started it up and got a white screen, but the question mark folder came up. So installed my 10.6 dvd and got the Apple logo and the spinning gear as always, but when it goes to go to the language selection screen, this is what i get.


I have checked the little LED's on the logicboard and all 3 on this model are lit up. As for the mini DVI cable to use an external monitor, i don't have one of those.

Is this a graphics issue with the x1600 video?

Once it gets to that stage, yeah it looks bad. But like i said before, when i turn it on, the apple logo, the gear and the folder with the question mark look ok. No screen distortion when those are on

Yes this happens when i boot from an installation dvd.
10.6 was the disc and right when it should ask what language i am using, that is the screen that shows up first.
Haven't tried my 10.5 Intel/PPC dvd yet, but will check that soon.
10.7 requires 10.6 so not doing that.

*UPDATE*

Well, created a 10.7 USB boot disk on my Macbook Pro and booted the iMac off of that, and i have had no screen errors, so i think it may have been a faulty install dvd that i have. So right now as i type this, it's installing.
Once that is installed, hopefully there will be no errors at all. *Fingers crossed*

Well install went fine, no screen glitches, but as soon as it restarts to show the Welcome video, that's where the fun begins.

One screen is the white screen with an arrow and 3 distorted lines.

Another is the black screen with an arrow only.

Another is a blue screen and 2 arrows. One that moves and one that stays in the corner.

Another time it was just a blank screen with nothing at all.

So now i know that it has to be the graphics once the ATI kext is loaded.

Well i have some good news and some bad news.

Good news is that i was able to install 10.7.5 on the iMac with little trouble.

Bad news, i had to boot into safe mode and disable all the ATI kexts and make it so that the GPU is running 2D only. So any 3D video animation and items of the sort is out of the question.
Right now System profiler says it's 5 MB video card.

ATI Radeon X1600:

Chipset Model: ATY,RadeonX1600
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 5 MB
Vendor: ATI (0x1002)
Device ID: 0x71c5
Revision ID: 0x0000
ROM Revision: 113-xxxxxx-139
EFI Driver Version: 01.00.139
Displays:
Display:
Resolution: 1440 x 900
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes

Click to expand...

But for surfing the web, checking email and listening to music, this mac does the job.

So i am happy about the new addition to my screwed up computer family.

Well, did alot of fiddling around with extensions and kexts, and this is what i have to share about failing ATI video gpu solder.

After many hours of going over what ATI driver will and will not work, i have found out that booting into safe mode and taking these extensions out and putting them into a folder called "Extensions Disabled" will allow your iMac to boot into normal mode and run with limited functionality.

I took out all the ATI drivers that were not needed for early and later models of the ATI cards, aka the x1300, x1900, 2000, 3000, 4000, 5000 and 6000 series cards.
I also took out ATIRadeonX1000GA.plugin, ATIRadeonX1000GLDriver.bundle, since with those in the extensions folder, those caused the video to heat up and glitch out.

These are the drivers that are currently installed to make the video work.
ATI1600Controller.kext,
ATIFramebuffer.kext,
ATIRadeonX1000VADriver.bundle,
ATIRadeonX1000.kext &
ATISupport.kext.
Those are the updated drivers supplied by the OS 10.7.5 update.

With those 5 extensions enabled, this is what System profiler now says about my video card.

ATI Radeon X1600:

Chipset Model: ATY,RadeonX1600
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 128 MB
Vendor: ATI (0x1002)
Device ID: 0x71c5
Revision ID: 0x0000
ROM Revision: 113-xxxxxx-139
EFI Driver Version: 01.00.139
Displays:
iMac:
Display Type: LCD
Resolution: 1440 x 900
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes
Built-In: Yes

Click to expand...

I also now have functional screen dimming and screen resolutions unlike before where i was stuck at 1440x900 and the screen wouldn't turn off.
Now it goes into sleep mode and i am very happy.

Pro's and cons of doing this.
Pros:
GPU doesn't heat up
full screen resolutions
can watch videos on the web *aka html5 and flash without any stuttering*
screensaver ability *though a little choppy*
ability to run a crippled iMac as if it were "semi" new

Cons:
no full OpenGL support
no 3D gaming support
Bootcamp and Windows will not boot with crippled video.