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IMac 2011 won't boot any OS

V

VenturaBoy

macrumors newbie
Original poster
Jun 5, 2023
10
0
Hey everyone,
I got a 2011 iMac that won't get past progress bar on any OS/hdd/ssd.
So far tested: old hdd with High sierra, ssd with win 10 - can't boot fully, only restarts at progress bar.
I even managed to install Ventura with oclp on new ssd but after root patching, I got the same problem.
Tried to reset NVRAM, SMC, nothing works.

Maybe some hardware or firmware lock?
Thanks!
 
Have you tested a freshly installed SSD or HDD yet?
Maybe the harddrive is broken or the partition scheme is damaged? Somehow it seems the culprit.

Maybe the EFI partition is damaged. If you can boot up from an installer drive you should first try to wipe the disk completely at first.
 
Yes, I tried with new ssd, connected internally or externally, it's the same. Also tried with fully patched and working Monterey ssd, only bootloops.
 
It's a far cry but you could look at your RAM. Are all slots populated right now?
Maybe one stick is faulty? Try removing all sticks but one and then try again.
 
Yes, tried that, everything ok. The problem is that (almost) any OS can be installed/working/booting only without patches/gpu drivers/acceleration.

Faulty gpu chip? Hw firmware?
 
Have you tried safe mode or internet recovery mode at all? Any issues with the display too, like graphical artefacts, coloured bands etc?

The 2011 iMac is known for GPU failures (I've had 3 with mine), so maybe that might be the issue. Have you had the machine for some time (by that I mean are you familiar with its history, use etc)?
 
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Tried to boot into safe mode, hangs on half of progress bar (left it for an hour 😂). Ventura via oclp is working, no screen glitches, green stripes etc., "About mac" says 6970m., but I think it's running on integrated gpu because as soon as I patch & restart it, I encounter bootloop. I'm not familiar with it's history, I bought it for parts but interested to learn what is wrong 😃
 
Could be the GPU then, but I'd have thought safe mode might have worked if that was the case (I thought safe mode disabled the GPU driver, but maybe I'm wrong or it uses it in a minimal manner - I think transparency effects etc looked funky on mine).

If you're happy to dismantle a little, there's some LEDs on the logic board that might help indicate what the problem is. I think they light up differently depending on the issue (like a Windows PC going through post).


Pages here are handy for tearing it down, if you haven't already:
www.ifixit.com

iMac Intel 27" EMC 2429 Repair Help: Learn How to Fix It Yourself.

Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2
www.ifixit.com www.ifixit.com
 
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hmm... If you bought it for "parts", maybe you are simply replicating the issue that made the seller realize that a "parts-only" status would help the sale.
 
Ok, can you tell me how am I using Ventura/playing youtube without gpu patches but fail to boot with them? Can I somehow check if some driver is disabled? Tnx everyone
 
VenturaBoy said:
Ok, can you tell me how am I using Ventura/playing youtube without gpu patches but fail to boot with them?
Click to expand...
I suppose that without the GPU patches, you’re just using the EFI framebuffer. Installing the patches causes the GPU to be used “properly” and things to go downhill.
 
An oven bake of the graphics card and a fresh application of thermal paste might bring it back to life for a while (milage varies). Mine's still going after a bake in July '21 (and a previous bake 14 months before that), but it's not exactly a permanent fix.
 
Bertrude said:
An oven bake of the graphics card and a fresh application of thermal paste might bring it back to life for a while (milage varies). Mine's still going after a bake in July '21 (and a previous bake 14 months before that), but it's not exactly a permanent fix.
Click to expand...
That can work in the short-term, however baking is not a permanent fix for AMD's stupidity (TLDW: AMD used the incorrect type of solder to connect the die to the substrate, lead to the solder cracking and killing the chip).

Cooking the card in the oven, especially the oven you use for cooking food, can pose some health risks, including solder and flux fumes.
 
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theMarble said:
There is an iGPU on the CPU package, however for a reason that goes over my head, it is disabled and cannot be re-enabled and used.
Click to expand...
It's actually enabled and used for QuickSync but it's not wired to the display. All display outputs are handled by the dGPU.
 
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theMarble said:
So then it's similar to how external display support was handled on the 15"/17" MBP from '11.
Click to expand...
Don't all dGPU-equipped MBPs from 2010 onwards handle it like this? iGPU for the internal display if dGPU is off, dGPU for the external(s)?
 
Amethyst1 said:
Don't all dGPU-equipped MBPs from 2010 onwards handle it like this? iGPU for the internal display if dGPU is off, dGPU for the external(s)?
Click to expand...
I think so. It may have been 2009 onwards, I think it started when automatic graphics switching was introduced.

I'm not sure how it worked for later (2012 and newer), but for 2010/2011's it worked like this:

- If only graphically-light apps were running (eg: Safari, Pages, Mail...) and only the internal display was connected, then the iGPU is used, and the dGPU is enabled, but "dormant" / not in use.

- If graphically-intensive apps are running (eg: Final Cut Pro, After Effects, games...) and only the internal display was conneted, then the dGPU takes control of the internal display and becomes the primary GPU. The iGPU is off.

- If only graphically-light apps were running, but external displays were connected, the iGPU would drive the internal display, and the dGPU would drive any, and all external displays.

- If graphically-intensive apps were running on all displays, the iGPU would be disabled, and the dGPU takes over as the main graphics processor for the computer.

I believe this was introduced in one of the dot updates to Snow Leopard (10.6.3/10.6.4 rings a bell), prior to this, only one of the two could be used at any given time, and you would need to log out and log back in to switch GPU's.
 
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VenturaBoy said:
So is it possible to get acceleration for iGPU on this iMac?
Click to expand...
theMarble said:
I'm not sure if it's possible or not to force the iGPU to drive the display on an iMac from this time period.
Click to expand...
It’s not.

theMarble said:
It may have been 2009 onwards, I think it started when automatic graphics switching was introduced.
Click to expand...
On a Late 2008 15” MBP: when I set the iGPU to be used all the time System Profiler said the iGPU also drove the external display.
 
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