Imac 27-inch Mid 2011 3.4 GHz Intel Core i7 16 GB 1333 MHz DDR3 AMD Radeon HD 6970M 1024 MB 1TB Hard Drive Yosemite 10.10 I just got a 27" iMac to use for design work for my company. It was used by one of my coworkers previously without any issue (to my knowledge). After setting it up two days ago, it started up fine and I was able to set up the computer. Over the past two days the iMac crashed twice - I forget what I was doing during the first one, but the second one was during a FaceTime call, when the person I was talking to switched from portrait to landscape. Finally this afternoon, while a youtube video was running, the computer shut down. When I attempted to restart, it would not boot. When I clicked the power button, the screen stayed black (NOT backlit - completely black), there was no sounds (like the start up sound), and the only noise I heard was the optical drive 'clicking' once or twice. Here's what I've tried: I don't have a copy of Yosemite, but since I head the optical drive, I placed my most recent version of mac into the optical drive to see if it would do anything with it. My iMac took the CD and now tries to run it for about a minute every time I boot, but the screen remains black and there's no sound (same as before). I tried resetting the SMC without luck. My keyboard and mouse is wireless, but I've tried resetting NVRAM using Command Option P R if that works with a wireless keyboard. I've tried multiple outlets in the house, and an alternate power cord. I tried removing the memory and booting without it. The computer beeps every couple seconds when started without the RAM (I assume to tell me just that), but no other activity. Reinstalled Ram and booted, and it does the same as before it was removed. Anyone have any clues to what might be going on or further troubleshooting I can do? Thanks!