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24inch White iMac - Graphics Card

R

RickNunn

macrumors member
Original poster
Oct 25, 2006
31
0
Hey, I've got one of the late 24inch white iMacs (2.16GHz Intel Core 2 Duo) & I've been having some problems with it lately which I'm pretty sure are the result of a faulty graphics card.

The system often crashes when doing large screen refreshes (ie panning in illustrator or switching to a new application.

I quite often get errrr bits of the interface left behind. ie when I shrink some thing to the dock bits of the part of the menu bar will still be showing

I also get some really really odd lines going across the screen, like rainbow colors almost, normally only about a pixel tall but some times the whole width of the screen. I get the odd pixel lit up too, but it's not a stuck pixel, as soon as I move some thing over it (ie make it refresh the data the pixel goes back to normal.)

I'll try and get some screen shots of it messing up if I can.

So my questions are:

A) Is there any kinda diagnostic tool that I can use to test to see whats faulty.

B) What graphics card is in my mac and can I replace it my self? (how hard would that be?

Thanks in advance to any one who can help me out.

Rick

P.S. the Mac is 4 months out of apple care :( and my nearest apple store is 1.5 hrs away, I don't really wanna drive that far for them to tell me it's going to cost me £1000 to repair or what ever. Oh thats a point, any one know what apple would charge for a replaced graphics card?
 
RickNunn said:
A) Is there any kinda diagnostic tool that I can use to test to see whats faulty.
Click to expand...

Use the Hardware Test CD/DVD that came with the machine, and run a full check. It does sound like a dodgey card, or perhaps the your RAM is poorly seated.

What I will say though, is whilst it's worth running, I've found the hardware test results to be...inconsistent, however it will hopefully at least help you identify what is the culprit.

AppleMatt
 
AppleMatt said:
Use the Hardware Test CD/DVD that came with the machine, and run a full check. It does sound like a dodgey card, or perhaps the your RAM is poorly seated.

What I will say though, is whilst it's worth running, I've found the hardware test results to be...inconsistent, however it will hopefully at least help you identify what is the culprit.

AppleMatt
Click to expand...

Oh great

Is that the OS disk (I upgraded to leopard) or is it a separate disk?
 
AppleMatt said:
Use the Hardware Test CD/DVD that came with the machine, and run a full check. It does sound like a dodgey card, or perhaps the your RAM is poorly seated.

What I will say though, is whilst it's worth running, I've found the hardware test results to be...inconsistent, however it will hopefully at least help you identify what is the culprit.

AppleMatt
Click to expand...

All I have is the Leopard disk (bought separately) and then in the original box I have install disk 1 & 2.

I booted from the disks, but I couldn't find a hardware test.
 
Sorry for the late reply, as CortexRock said, use disk 1 (that came with your machine) and hold down 'D'.

AppleMatt
 
AppleMatt said:
Sorry for the late reply, as CortexRock said, use disk 1 (that came with your machine) and hold down 'D'.

AppleMatt
Click to expand...

Cheers guys, I tried this first thing this morning (after my computer had been off all night) and it came back with no problems, But then I only get the problem when my computer has been on for a while and I have been working hard on it.

So I will try again at the end of the day.
 
Well I have tried the hardware test a whole bunch of times now, and it comes back with nothing wrong every time :(

I did notice yesterday though that when I remoted in to my computer via VNC I still had the strange distortion on my screen. I think I'm correct in saying remoting in with VNC wouldn't use the graphics card at all?

So my question is, do we think this is a RAM issue?
 
Could be RAM, could be corrupt graphics drivers.

Have you got Windows on there? Does it do it in Windows?

A wipe and reinstall is always an option.
 
AlexisV said:
Could be RAM, could be corrupt graphics drivers.

Have you got Windows on there? Does it do it in Windows?

A wipe and reinstall is always an option.
Click to expand...

Hey AlexisV, thanks, I don't have windows. But I have done a fresh install, since the problem started so i doubt its the driver.

I have another iMac, think its worth me swapping the RAM over and seeing what happens?

Could it possibly be the connector from the RAM to the logic board? if the RAM isn't faulty.
 
So now I've replaced the ram and I'm still getting the same problems :(

So what's left? faulty logic board?

I've done a couple of screenshots of what the mess I'm getting on my screen looks like if that helps any one?

1.jpg


2.jpg
 
Looks familiar. I have the exact same issue with my 24. Try to keep a fan running nearby that allows the hot air to escape the area. I've noticed that when I can reduce the operating temp the glitches are all but gone.

I think the only cure to this is a logic board replacement.
 
You may want to give smcFanControl a try. It allows you to run the fan faster. I just started having this problem on my 24" 2.8 aluminum iMac while editing a 9.5GB file in iMovie. Still under warranty though.

Edit: I'm 99% sure this is the graphics card. Anyone have a second opinion?
Screenshots
 
iMac bad video card

I saw the same bad video problem on a 24" iMac. It was a bad 7300 video card. I was able to replace it with a 7600 from welovemacs.com.

See my post about the process:
http://www.techdc.com/?p=336

It took several hours and isn't easy. But if you are adventurous, you can try it.
 
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