Origineel bericht door: Simon Jones ,
Dear jakobk, I have the same issue, but slightly different. I started with a 2013 system. for reasons that are explained [https://forums.macrumors.com/threads/imac-2013-cpu-upgrade.2058419/|here] I changed the CPU for the 4790. Mine too won't boot up. So I have a new CPU and a new mother board and it still won't boot. I'm interested in your progress, what you eventually did and if you confirmed the lack of compatibility with the CPU.