Solved Replaced Cpu Mac Seems Dead Led 1 On Led 2 Goes On Off On Imac Intel 27 Emc 2390

Chosen Solution

Hi all. Wanted to replace my i5 3,1 GHz with a I7 3,4 GHz ( a 2600 model) , replaced the logic board, but mac doesn’t turn on. Replaced the known good i5 3,1 GHz, but same problem. LED 1 is ON, LED 2 goes on and off (cycling) w/ short fanspin. Anyway I can measure the PSU for defects? Any other steps / defects I should check?

Both were good known CPU’s , the problem ended up being dust in the RAM seats. cleaning them and reseating the S0DIMMs solved the problem.