iMac stuck in boot cycle with vertical yellow lines
I've been using my iMac since 2011. However, I was recently on my Mac when it suddenly shut down. It automatically restarted and showed the following screen (note the vertical yellow lines)
The boot process seemed to continue but I was then left with a blank white screen as seen below:
This screen lasted for about 2 minutes then the computer restarted and the process has been repeating ever since, never progressing.
I have both looked online and have contacted Apple Support directly. I have tried a number of things as listed below:
- [§] Resetting the NVRAM (Resets but does nothing)
- Booting into safe mode (Doesn’t let me boot into safe mode)
- Booting into recovery mode (Doesn’t let me boot into recovery mode)
- [§] Booting from a bootable flash drive with a fresh install of OSX loaded (Doesn’t get past opening the image before restarting)
However, one of the big problems is that I only have access to the bluetooth mouse (and a separate USB mouse) that was supplied with the iMac so have only been able to confirm that the procedures above marked with an [§] have worked whereas the other may not have worked as the bluetooth keyboard may not have been connected at the time. I do have a USB keyboard on the way but have looked to this forum as I admire the values that iFixit upholds and would really appreciate some advice on what to do if this is not a software related problem.
Many forums debating the same problem have pointed to a failed GPU as the cause of this problem. However, I am hesitant to jump to this conclusion as this was in no way a gradual process, it happened instantly. Despite this, I am no expert on hardware as I focus more on software and would love it if someone could point me in the right direction of what to do if the GPU is the problem. I have seen this iFixit article here which explains the process of replacing a graphics card for my model of Mac. The technical speficiations for my Mac are the base options listed on Apple's website here.
My question is; if I do have to replace the graphics card, would it work if I bought a second hand one such as the one listed on eBay here and then follow a guide such as the iFixit one above to replace it? If so would I have to take other factors into consideration such as whether or not the previous GPU was from a Mac or a PC? And finally, would a GPU replacement almost be guaranteed to fix my problem?
I understand this is a lot to ask but I am really worried as a lot of my work is stored on the iMac and I also do not want to lose something I spent a rather lot of money on.
Thank you in advance for any help or guidance,
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