Chosen Solution

Hello, my iMac appears to be having hardware issues. I thought it was a power supply issue, so I bought one from this website, but I’m getting the same issue. LED 1 lights up and stays lit, LED 2 blinks 1 time, LED 3 and 4 both do not light at all. Also, when LED 2 blinks both fans spin for about 3 seconds, then stop. This process never stops as long as the power cord is plugged in to the wall. Ive tried all the typical fixes, reseated RAM, reset SMC, pram, and replaced the power supply. I’m thinking it’s the logic board, but I can’t find anything online with these same symptoms. Any input would be much appreciated. Thank you

The first LED means your power supply is fine. -it should always be on when the power is plug in. The second LED means your logicboard is fine. -it should aways be on when your computer is on. The third LED means your video card is one. If your second LED doesnt stay on that means you have a logicboard issue.

Just found the fault. Remove your ram vacuum and clean the slots, clean ram and fit 1 ram at a time, I removed the ram I upgraded 2 years ago now it boots up. from my research if you still have issues it will be a logic board but check your ram first

I had same issue and same led pattern. Like a dummy, I had LCD thermal sensor cable plugged into the unused port to the left instead of the port next to the Display data cable/LCD cable.