Graphical errors and system stalling at boot up
Hi everyone. I hope someone here can help me nail the issue here with my iMac. I have a range of symptoms, that doesn't really pinpoint to anything specific I think, besides perhaps some global components like the motherboard.
How it started:
Found my computer today completely black. It was on earlier, and it looked like it had done a serious crash. I shut it down by holding in the power button for a while and then I it started again.
It starts with a chime, meaning (POST) internal tests came through right?
Now it started off with bars or thin green lines repeated regulary vertically.
(image shows verbose startup)
When the apple shows up, the distortion changed into small squares that covered the screen in a repetitive pattern.
That is usually as far as it will boot. Although once it got to the user login screen, but froze there.
Throughout the issues, I am able to move the mouse on the screen. Even if everything freezes. The energy saver dimming of the screen works.
Second screen connected will flicker yellow and white.
I was not able to boot up emergency disk partition.
But was able to boot up the install CD once. The graphical issues went away then, and I ran repair disk/repair perms with out any help. Later attempts to do this have failed.
I was not able to boot up a separate system on a usb disk. It freezes into the apple part of the process.
Was not able to access ATH. It froze later in before anything showed up.
I've reset the SMC and PRAM.
I've disconnected everything except ethernet, mouse, keyboard.
The mouse cursor hovers above the graphical artifacts. So its not the screen hardware.
Conclusions so far:
- If it was a hard disk issue, I shouldn't have any problems booting from a CD right?
- If its a graphics card issue, It shouldn't freeze at the apple logo? Can graphics card issues cause system freezes? Since I was able to move my mouse, that means its not a full system kernel panic right?
- power supply?
- faulty ram?
- It kind of feels like there is some corruption in a hardware component firmware or something.
- Don't think its heat related as I had it off for an hour to see if that help, and it didnt.
Would really appreciate any help on diagnosing this, as I will have to cash out for repairs, or hopefully do it myself.
Is this a good question?