My iMac 27" purchased in 2012 is running Mavericks OS. I did a software update last week, and switched on the machine for first time since then, today.
I get 4 or 5 green vertical bars down the start-up screen with the apple logo and timer running. The screen then goes to a grey screen and just hangs.
Tried safe boot and nvram clear but did not work. Will try again this evening.
iMac
JamesBKK wrote:
Tried safe boot and nvram clear but did not work. Will try again this evening.
Hi, try as well: Intel-based Macs: Resetting the System Management Controller (SMC)
Cheers
Have the same problem , I thought it was from El Capitan upgrade , it's a video card issue , I'll save you the trouble of a visit to the Genius Bar . They know exactly what it is but run lots of tests and give lots of stories but it's the card.
It could be a video card issue. If you have a AMD Radeon HD 6970M video card you could be part of this replacement program: iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program - Apple Support. It all depends on when you purchased the iMac.
iMac will not boot, green vertical lines on screen
