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Did my logic board fail or video card?

D

dinggus

macrumors 65816
Original poster
Jan 17, 2012
1,313
65
I have a 2009 iMac 27", it froze on me, I restarted it and it happened again. The second time I restarted it, it froze on boot like 3/4 loaded and then I have a bunch of lines running across the screen.

I figured this would be the logic board, so I found a used one on eBay. Sent the person a message with a photo of my screen and they told me they believe it's the video card that failed and not the logic board.

How do I know which failed?

https://imgur.com/DcOXlY1
 
Between the two parts, the video card is probably the likely failure.
But could also be the logic board, so it's still a guess.
As you have to pull out the logic board to get at the video card (and if you have already purchased a logic board) I would try replacing the logic board. It's not a simple job, either way.

BUT, I would suggest first trying different RAM sticks. Way cheaper (and much quicker), and COULD be your issue. You might test that theory by reseating your existing memory sticks, and see if your graphics issue changes in any visible way.
 
DeltaMac said:
Between the two parts, the video card is probably the likely failure.
But could also be the logic board, so it's still a guess.
As you have to pull out the logic board to get at the video card (and if you have already purchased a logic board) I would try replacing the logic board. It's not a simple job, either way.

BUT, I would suggest first trying different RAM sticks. Way cheaper (and much quicker), and COULD be your issue. You might test that theory by reseating your existing memory sticks, and see if your graphics issue changes in any visible way.
Click to expand...

To reset the memory sticks, just pull them out and plug them back in?
 
Yes, simple as that - you have the right idea!
I would probably swap the sticks between slots - but the idea is to do the simple remove/reseat to possibly eliminate some minor corrosion on the RAM contacts as a "contributor" to your problem.
May not make any difference, but won't hurt anything.
And, a few seconds for a task that (possibly) can fix your issue - without spending any money, too!
 
DeltaMac said:
Yes, simple as that - you have the right idea!
I would probably swap the sticks between slots - but the idea is to do the simple remove/reseat to possibly eliminate some minor corrosion on the RAM contacts as a "contributor" to your problem.
May not make any difference, but won't hurt anything.
And, a few seconds for a task that (possibly) can fix your issue - without spending any money, too!
Click to expand...

That didn't seem to work.
 
dinggus said:
That didn't seem to work.
Click to expand...

In case it's ram, you could always try something like memtest. Run it for 10 cycles or so. If it turns up any error, that can explain issues. Graphics artifacts are usually gpu related though. Make sure the cost is reasonable relative to the age of the machine. I wouldn't personally drop hundreds of dollars on anything.
 
If the RAM reseat didn't change anything, then you have to proceed to other possible repairs (assuming you still want to fix your iMac.). Your next step will be the logic board. And, also correct that the video card has possibly failed. It ALL has to be removed to get to the video card, and quite a job just to reseat the video card. That's what I would try, but if you already have a replacement logic board, then you would use the old video card on the replacement logic board.
If the problem continues after the logic board has been swapped, then you know it's a video card.
There's really not a specific test that you can do with this kind of problem, other than to try swapping parts - although, more often I think, the video card will be the faulty part.
 
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