Thought my mid 2010 27" iMac quad-core i7 was gone for good!
My local power company provides a very lacking service, so get occasional blackouts often. I had previously bought an UPS to prevent blackouts, but somehow the UPS died, and I was left with my iMac directly plugged in the wall socket for about 2 months. One day, we had a power outage, and then the iMac didn't turn on anymore, no noise, no beep, no screen, nothing.
I was in shock, thinking the iMac was dead. First thing that came to mind was maybe the power supply was damaged. Off I went to search where and how to replace it. I found ifixit, its guides, along with the part I needed to replace and decided to give it a go.
The repair was quite simple, since I already had the suction cups to take the glass away and also the torx screwdriver to release the screws. Followed the video + picture guides and in 20 minutes I was done, jumping with happiness in my room.
Later, I have stressed the machine running games, benchmarks, and so on, to make sure the power supply was working correctly. Definitely saved my life and my precious money.
The power supply I have taken from my iMac doesn't look exactly like the one ifixit sells. My was made by LITEON. But worry not, it works perfectly. ifixit guys for sure know what part is right for your iMac, even if it seems a little different from the outside.