Just had a breaker trip and I was unable to start my iMac afterward the power came back -- I had the same exact issue a few weeks ago after an outage -- in a different apartment (so it's probably not the electric from the outlet at fault) Hitting the power button causes the drive to spin up and fans to go on, but no chime and no screen. Resetting the SMC does nothing. Same results. However, I was able to remove two of the four SO-DIMM modules (the two on the right side) and the system booted. I powered it down and put the RAM back in and it booted fine. Any ideas? Logic board? Did I just need to clear the RAM in order to get it to go? I've not experienced anything quite like this before.