I have an iMac 27" 2015 that's been causing me so many issues. It will randomly hard-shut while doing any random task, browsing the internet, typing a document, playing games, etc..It was very hard to reproduce as it would happen spontaneously, and had been that way for a while, but it started getting worse and the shutdown became reproducible. I brought it in for repair and they said that they were going to replace the power supply. That worked for a couple of days but it went right back to the same problem. Then I brought it in again and they held the machine for over a week. They put in a new logic board, which failed, then put in another logic board to replace that one, which is what I have in this machine now - only to fail again. So a power supply later, 3 logic boards later, the issue is still at hand. I called up Apple and talked to a supervisor and he told me that I can bring it in and have the logic board replaced for the 4th time.. Isn't this absolutely ridiculous? As I was sitting with the technicians, I told them I knew exactly what was going to happen, and it happened twice, and yet they still want to continue with the same thing. Am I just going to have to constantly go through this? Really not sure what extra steps can be taken here.