Hello guys, I am now couple a days into research and trial-and-error into repairing my iMac 2546. I want to apologise if there was a simmilar thread, but cuz I havent wound a solution yet I started this one. So, On boot, shows apple logo and one second later either panik or double panik, shows different panik reports... Tried: -Changing RAM -Changing HDD -Boot from external None of the above showed any change -Swaping cpu- i hat i5-2400s - could not boot at all, black screen with no sound,but hdd and fan works. -Apple hardware test, both short one and extended showed no troubles -Installing new OS- doesnt show kernel panik in boot option menu, until I select installation media, then panik -Apple Recovery- starts Internet recovery automaticly, shows rotating globe,loads first thick bar, and then wont show next step. -Holding CMD+Option+P+R, until second chime, first time I done this, I was able to boot up into system, but iMac frose 5 seconds afterwards. -Pluging AC kable out, holding Power button for 5 seconds, pluging back AC cable None of the above helped or worked. I dont know what to try next, so please if anyone has a suggestion or advice, please share.. Thank you!! --- Post Merged, Jun 11, 2016 --- Not 5 minutes into writing this thread, I somehow managed to get it working!!! For all you guys with similiar issue, it was an EFI, or EMI, or something with E, error on hdd, which I fixed by holding COMMAND+R on boot, then into Disk Utility-First Aid-Disk Verify-Disk Repair!!! Cheers!!