Resolved iMac 2011 died. Trying to find out what the problem is.

[krazzix]

My iMac boots, but the screen stays black. I hear the startup chime but the screen stays black. The backlight is not the problem, there is nothing visible when using a flashlight. I tried resetting PRAM and SMC, nothing. I cleaned the iMac of dust on the inside (surprisingly little after 9 years of use) I replaced the PRAM battery, nothing.

The GPU was replaced with the replacement program I think somewhere in 2014. It showed green lines all over the screen. This is not the case now, it's just black.

An external screen shows nothing either.

Since I have no screen I can't run any self-test or anything, I hope anyone can advice me with the little information I have.

My own guess is it's the video card, so I could replace it (or put it in the oven, which is known to help sometimes), but I'm not sure. Would it be a good idea to try to replace it anyway?

Specs:
iMac 2011 27"
Intel i7 CPU
6970m 2GB GPU
8GB RAM
256GB SSD + 1TB HDD

 

[T'hain Esh Kelch]

I could imagine that Apple were replacing the faulty cards with the same kind of cards, still containing the fault, as they have done before, so a black screen is likey due to the GPU.

Personally I have baked my 2011 iMac GPU four times now, over 3 years, and I am writing from it now.

 

[krazzix]

Personally I have baked my 2011 iMac GPU four times now, over 3 years, and I am writing from it now

And what were the symptoms when it stopped working? Also a black screen, or messed up display?

 

[T'hain Esh Kelch]

I've had both. I also know a white screen can occur.

 

[Bertrude]

If it's any consolation, my 2011 iMac's GPU died the other week. It also was replaced by Apple just over 4 years ago. I got colour hue shifts and vertical lines mostly, or shut downs.

I baked the GPU in the oven 2 weeks ago and it's working ok for now although GPU die temps get to the top 70's (C) when gaming or viewing full screen YouTube for a while.

I went down to a local computer shop and they quoted me £300 for a logic board replacement that included a refurbed GPU. I decided I didn't really want to throw more money towards a 9yr old machine, so did the oven thing as I didn't really have much to lose.

 

[DLary]

If you have access to a displayport monitor, try connecting it to the Thunderbolt port on the iMac.

 

[krazzix]

I found a repair document for the 2011 iMac, and there are 4 leds on the main board that indicate certain problems. If only the first 2 leds are on, there is something wrong with the video card. Which was the case.

So my suspicions where confirmed. So I took the video card out and put 10 minutes in a pre-heated 200º oven.

And it WORKED!

Total cost of repair: €9,15 for the thermal paste. ?

Thanks guys!

 

[Bertrude]

Glad it worked for you too, hope it hangs on in there

 

[rc3105]

When you get tired of baking that card over and over take a look at this thread

2011 iMac Graphics Card Upgrade

iMac 2009 to 2011 MXM3 graphics card upgrade (Lastest update 10/13/2023 - this is the official documentation page - you found it finally!) This is the single and only documentation post. During the last years we constantly updated this post to reflect the lastet development of vBIOS and OCLP...

forums.macrumors.com

I'm running Catalina on a K1100m which is faster/cooler and it was a whole $20 on ebay.

 

[krazzix]

When you get tired of baking that card over and over take a look at this thread

I'm waiting for the new iMac to come out. I'll bake it until then ?

 

[macguru9999]

its probably the gpu again. best to buy a second hand thin imac and not bother with baking. its a hassle getting the gpu out and back, and you dont know how long you will get before it refails.

 

[krazzix]

Personally I have baked my 2011 iMac GPU four times now, over 3 years, and I am writing from it now.

its probably the gpu again. best to buy a second hand thin imac and not bother with baking. its a hassle getting the gpu out and back, and you dont know how long you will get before it refails.

Replace the HDD with an SSD, and the GPU won't fail again. Source:

Mid-2011 iMac: Graphics issue... again.

Absolutely 100% I've replaced the HDDs on hundreds of late 2009–2013 iMacs within 5 years in schools. Over 100 were the 2011-12 with the supposed GPU problem. The reason we did this was it was less expensive than having me do yet another service call when the HDDs fried. Total number of GPU...

forums.macrumors.com

 

[T'hain Esh Kelch]

Replace the HDD with an SSD, and the GPU won't fail again. Source:

Mid-2011 iMac: Graphics issue... again.

Absolutely 100% I've replaced the HDDs on hundreds of late 2009–2013 iMacs within 5 years in schools. Over 100 were the 2011-12 with the supposed GPU problem. The reason we did this was it was less expensive than having me do yet another service call when the HDDs fried. Total number of GPU...

forums.macrumors.com

I might try that. My HDD just failed 5 days after I did my last GPU bake.

 

[herrdude]

Replace the HDD with an SSD, and the GPU won't fail again. Source:

Mid-2011 iMac: Graphics issue... again.

Absolutely 100% I've replaced the HDDs on hundreds of late 2009–2013 iMacs within 5 years in schools. Over 100 were the 2011-12 with the supposed GPU problem. The reason we did this was it was less expensive than having me do yet another service call when the HDDs fried. Total number of GPU...

forums.macrumors.com

Well, in my case I baked my card and put in a SSD. The graphics card died again 5 months later. There is no way getting around it, these are defective graphic cards. Even cards that were replaced by Apple die eventually. What surprises me is that for all the effort it takes to bake a card, you can go a step further and install a solid, reliable graphics card.
I installed a NVIDIA K2100m for $40US and it runs beautifully. For more info: https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/

 

[insydney]

Well, in my case I baked my card and put in a SSD. The graphics card died again 5 months later. There is no way getting around it, these are defective graphic cards. Even cards that were replaced by Apple die eventually. What surprises me is that for all the effort it takes to bake a card, you can go a step further and install a solid, reliable graphics card.
I installed a NVIDIA K2100m for $40US and it runs beautifully. For more info: https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/

was this a straightforward instal, are there any downsides, like brightness control ? i see no reason in baking a AMD gpu just to have to do it again 6 months later as is often the case

 

[rc3105]

The K2100m and K1100m have brightness control if you use the OpenCore boot loader mentioned in that thread.

Flashing the firmware may seem challenging but it's really pretty easy.

-
Riley

 

[insydney]

rat's... i was hoping you weren't going to say that... not in my skill set yet, although I've managed it with my phone.

 

[rc3105]

No need to buy a programmer there's instructions in the thread and a linux image.

Write the image to sd, boot from it, flash the video card. Piece of cake.

 

[insydney]

perfect thanks it's on my 'to do' list... pity apple took so long to sort the overheating issue out destroying 1000's of the AMD GPU's on their way. i'm in australia and heat is an issue during at least 4 months a yr
so you recommend the K2100 ?

 

[rc3105]

I'd go with the K1100m.

The K2100m is larger, harder to mount, pulls more power and can cost quite a bit more. It's a little faster but they're both 2013 era so the speed difference is miniscule by current standards.

There seem to be variants (of both models) that don't work in iMacs so be sure to buy from a seller that offers free/reasonable returns.

 

[insydney]

I'd go with the K1100m.

The K2100m is larger, harder to mount, pulls more power and can cost quite a bit more. It's a little faster but they're both 2013 era so the speed difference is miniscule by current standards.

There seem to be variants (of both models) that don't work in iMacs so be sure to buy from a seller that offers free/reasonable returns.

thanks for the sound advice. living in australia has disadvantages when buying online, shipping is very expensive and from USA , and it's dodgey buying from china. this applies to everything unless you know the seller... so returning something is out of the question