Logic board or GPU failing? Help determine please!

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Logic board or GPU failing? Help determine please!

Recently my late 2009 27" imac crashed and upon restart I got a grey screen. Tried all the usual remdies - NVRAM reset, pulled the plug out the back, took out the added RAM and then later the stock RAM - but nothing got in going again. Booted in safe boot and I get the desktop but there are 5 pink/grey 1/2" vertical stripes across the screen - like viewing the screen behind prison bars. Called Apple support - not much help other than telling me to take it to a shop. Here in Nagasaki, Japan nobod touches MACs. Closet Apple store in Fukuoka is a 2 hr. drive (plus about $120 in highway fees and gas) so that's not a great option. I asked if it was the logic board then how much for repair - about $850 so that's rediculous for a 4 yr. old machine.

I did come across some instructions on macfixit on how to replace the gpu. Many say it's soldered to the logic board and therefore the whole thing must be replaced. I found this part online - an AMD Radeon HD 6770M, 512MB card for about $200. Seems compatable with this imac. So, my questions are: is it the gpu that is failing/failed and if so, will this Radeon card fix the problem?

Right now the mac is fairly limited in function - can use the net but those bars are ugly and visually impairing. At least I'd like to use it as a music jukebox and hook up to my living room stereo but sound output is disabled in safe boot. Anyway to stream the sound files to something? Thanks for any advice

Posted on Jul 27, 2013 8:03 AM

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Answer 1

Best reply

mende1

Level 10

93,538 points

Jul 27, 2013 8:07 AM in response to Danny Louviere

Your symptoms are the same I had when my iMac got the GPU damaged. The GPU is damaged.

Late 2009 and newer iMacs have got a removable GPU, so you don't need to replace the logic board. Also, the GPU of the iMac isn't expensive, so the repair will be cheaper than you thought.

Apple only allows to install the same GPU that came with the iMac and at an Apple Store or reseller. However, if your iMac isn't in warranty and you want to do it yourself, you can follow the iFixit steps and install the GPU yourself. As you said, the AMD Radeon HD 6770M is compatible with your Mac, and you will get a better GPU, but I recommend you to read the relevant parts > http://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2309+or+2374+Graphics+Card+Up date/9553/1

This is dangerous, so take it to an Apple Store always that you can

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Answer 2

Jul 27, 2013 8:55 AM in response to mende1

Thanks for your quick reply mende 1. I'll check with an APple repair shop and see what they would charge to replace the gpu. I may pick up the radeon card online and see if they would install it for me. SOunds a lot cheaper than the original $850 Apple support quoted me.

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Answer 3

mende1

Level 10

93,538 points

Jul 27, 2013 8:56 AM in response to Danny Louviere

Good luck

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Answer 4

Jul 29, 2013 4:24 AM in response to Danny Louviere

I had the same issues as you. Took it in to Apple who confirmed it was the gpu or the logic board. I looked into replacing the gpu myself it is possible but is not simple. It is important to get the apple version of the graphics card as only this one is compatible due to the firmware that is embedded on the card. Must confess it was cheaper to get apple to replace the gpu than me do it myself as the graphics card was going to cost me £250 and Apple would replace the card and install it for under £200. Personally I think Apple in the uk know there is an issue and as such are offering a repair at a reasonable price. In the UK we have pretty good consumer rights as a result of which my 2011 iMac is now the the person that I bought it from I look forward to seeing where things go. If you are going to do the job yourself you could look into getting the gpu reballed. This could fix the problem but you would need to look further into this

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Answer 5

Jul 29, 2013 6:33 AM in response to Sean_Keeling

Thanks Sean for the info - that is a bit of important info about the firmware. I'll have to check with Apple here and see what it'll cost for a gpu replacement.

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