Ok, so I picked up a cheap 21.5” mid 2011 i5. Seller listed it as graphics problem and HDD removed. Firstly before doing...

So I've been refreshing old iMacs. This particular mid 2011 27” was working fine including the SD card, after installing...

Hi all you smart iMac enthusiasts I also have a 2011 27” (2429) iMac with no display fault (black screen). After reading...

Seems to be a software issue in High Sierra that coincided with the auto update and boot rom update. Before resorting to swapping U6100 bios chip I decided to try a internet recovery to Osx Lion, even though the installation failed, it was still on the installing bar some 12hrs later, after a forced reset and loading to my Snow leopard bootable USB, which BTW didn't work on this mid 2011 imac, the SD card is displayed in the list of disks and the SD card reader LED is now off. I will try to reinstall HS again as hopefully this failed Lion install has solved the problem. EDIT: High Sierra install with SD still working yes!! Will go through the updates and hope survives. EDIT 2: Happy to report after applying all the updates the card reader is still working. Strange that the updates go in order of 2020-005, 2020-004, 2020-006? Guess its a apple thing…

The 27” heatsinks are not all the same. For a 2GB card you would want the 3 pipe variant of the heatsink otherwise you risk cooking your card.

https://support.apple.com/en-au/guide/mac-help/mchlp1413/10.14/mac/10.14

I just tried to install a GTX 880m apparently its a ex Dell card. My problem is the iMac will not even power on with the internal lcd connected. Led1 will stay lit and do nothing, disconnecting the LVDS cable the iMac boots fine to a external monitor via mini dv cable. It the 880m flashed fine via terminal, i tried re-flashing but makes no difference. If i hot swap the LVDS cable then reboot i can get the internal lcd to work however if i shut down and power back on i get the boot chime loop over and over. My guess is the card just isn't compatible.

Old thread but my mid 2010 27” is 11 years old and the PRAM battery still works fine.

No way!!! I’m so happy. I have a working 2011 27” i7 imac with 16gb ram for $76 USD plus paste and pads. It must have been the LVDS flex cable. By fully removing it from the lcd panel for the photos and then putting it it back I reinstalled the panel and was going to do the flash light test on the desktop when to my delight a white screen ? I have had that panel in and out so many times but had never full removed the flex cable, maybe it was loose at the connection to the lcd but it looked sweet and taped down ECT. If this problem persists I'll buy a new cable, until then im happy mac'n. Thanks for everyone's input and i hope this might help others in the future.

LCD side MLB side I appreciate the help, thanks everyone, keep the suggestions coming. EDIT: looks like maybe some pulling on the back of the MLB side connector? It would be nice if they sold an adaptor to go from 2010 to 2011 connected type, wishful thinking. EDIT: logic board socket