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This iMac’s graphics card was repaired/replaced by Apple twice since I bought it for FREE. Same problem came up around January this year 2020 and now Apple refuse to repair it due to obsolete reasons. They referred me to a third party repair shop. So I decided to buy 2Gb graphics card from ebay. When I installed the new card, I’m having a loading apple logo then white screen. Below is the iMac specs before I put the 2Gb graphics card. OS: Yosemite, 3.4Ghz i7, 1Gb GPU RAM: 12GB (8GB was added) SSD: 1TB I tried all the keyboard shortcuts, to reset RAM, reset SMC, utility diagnostics using disk, etc. None works. This is the 2Gb GPU I get from ebay - https://www.ebay.com/itm/AMD-Radeon-HD-6… Question: Could someone please provide advise what I should do to get pass the apple loading logo? I would really appreciate for any inputs. Thanks
I’m suspecting you have a defective GPU board. What does the onboard diagnostics LED’s telling you?
Here’s a breakdown of the onboard diagnostic LED’s: LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty. LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly. LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement. LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.
Here’s the 2GB one I bought last month (installed 10 days ago because it took almost a month to get out of Hong Kong even with a $30 shipping fee). NEW 661-5969 661-5968 Video Card AMD HD 6970M 2GB For iMac 27" Mid 2011 A1312 https://www.ebay.com/itm/NEW-661-5969-66… I had no problems with it running just fine with Sierra on a Apple iMac 27-Inch “Core i7” 3.4 (Mid-2011) SpecsMid-2011 - MD063LL/A - iMac12,2 - A1312 - 2429 16GB RAM 1TB SSD 2.5” Crucial MMX500 upgrades Try booting from an external USB device.
