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Chris.

macrumors regular
Original poster
Aug 22, 2008
124
1
UK
Hi, recently my 20" iMac has been showing some strange graphic problems when starting up, it doesn't happen all the time. Its hard to explain, what it looks like so I was able to capture a video of it on my iPhone, it happens near the end of the boot cycle;

Here's a link to the video;

http://www.twitvid.com/W2ERC

I've tried clearing the PRAM etc and no luck. The iMac will be two years old this August, I don't have AppleCare.

Do you think the video card is dying?

Thanks,
Chris.
 
Hi,

Yeah, I tried the Apple hardware test from the Snow Leopard CD and also the one from the AppleCare disk (which I got for my MacBook Pro) it found no issues at all. The Installation of OS X is fairly new too, I think it was the end of March I reinstalled.
 
Hi,

Yeah, I tried the Apple hardware test from the Snow Leopard CD and also the one from the AppleCare disk (which I got for my MacBook Pro) it found no issues at all. The Installation of OS X is fairly new too, I think it was the end of March I reinstalled.

Did the problem exist before you reinstalled OS X? Does it only appear while booting? It could be a corrupted system file thus I'd reinstall OS X
 
Nope, its only started happening the last couple of days. I will create an image of my installation and install a fresh copy of Snow Leopard, and then see if it occurs. That way if it does still occur, I can easily go back.

I have however, noticed graphic problems when actually running OS X, like once I moved a window and it went all distorted. Also, it was on my 2nd monitor. Hasn't happend again tho.

Any other suggestions would be great, thanks.
 
This should be clear that you must post at least which gfx card is in your imac...

is it the HD2600 pro?


To test your video card it is best to play games and see what turns out. They very very best way is to install Windows via bootcamp and play something like Left4Dead. If errors occur, it is your gfx card. If not, it is something else OR it is just a glitch that you dont have to worry about. My desktop has that glitch, but it has it with different mainboards, different gfx cards, different cpus, different PSU, but it is all one installation of Windows.


I alos have a 20 2.66 imac.
 
Sorry, yes its the ATi Radeon HD2600 Pro.

I've got Steam installed on my iMac so I will play the free game Portal that came with it and see what happens.


EDIT, wow after playing for a few minutes this happend;

113963320-51bcd0bfefb23451eebaacd71cc39d94.4c125d80-full.jpg
 
Sorry, yes its the ATi Radeon HD2600 Pro.

I've got Steam installed on my iMac so I will play the free game Portal that came with it and see what happens.


EDIT, wow after playing for a few minutes this happend;

113963320-51bcd0bfefb23451eebaacd71cc39d94.4c125d80-full.jpg

That indeed seems to be your GPU. If you're still under warranty, give Apple a call. If not, give them a call anyway, if I recall correctly, the GPU is not integrated nor soldered thus swapping it doesn't involve a new logic board (a lot cheaper)
 
That indeed seems to be your GPU. If you're still under warranty, give Apple a call. If not, give them a call anyway, if I recall correctly, the GPU is not integrated nor soldered thus swapping it doesn't involve a new logic board (a lot cheaper)

no wonder nvidblows 9400m replaced this **** from a great company :p (not saying nvidia sucks 9400m dies.,)
 
Looks like your video card is overheating, what you need to do is open your imac, and clean all the dust thats been accumulating.. There also might be a chance your video card is damaged now due to the overheating.. but I would open it up and give the cleaning a go.. What your getting is artifacts, which usually occurs from overheating or when you overclock your video card too much..

Anyway, good luck :]

PS: ATI makes great video cards, but some of both ati and nvidia cards draw a lot of heat.. infact your better off with ATI, because nvidia lately has had a high failure rate with some of its gpu's these past two years, they lost a lot of money due to this.. so just because the HD2600 is failing doesn't mean ATI isn't a good company :p
 
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