iMac powered but won't boot

[tyhoerr]

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!

 

[Natzoo]

I don't know, it seems too complicated for my knowledge, i highly recommend you take it to apple

 

[DeltaMac]

This may help you, as you discover the road to your local Apple store, and your respective "genius":
http://support.apple.com/en-us/HT203787

Apple should replace your graphics card with no great difficulty.

 

[tyhoerr]

@DeltaMac - That's very helpful! Question though: will GPU failure prevent the iMac starting up (albeit without display)? I tried starting it up and waiting a few minutes, then entering my password and trying to eject the cd I have in the optical drive with the button on the keyboard. The iMac didn't respond. I figured it should still be 'running' even without the GPU working, just without any display. This makes me worry there could be something else going on - or am I wrong?

I'd like to not have to worry my employer if I don't have to Knowing it's something Apple will replace would be helpful!

 

[yjchua95]

@DeltaMac - That's very helpful! Question though: will GPU failure prevent the iMac starting up (albeit without display)? I tried starting it up and waiting a few minutes, then entering my password and trying to eject the cd I have in the optical drive with the button on the keyboard. The iMac didn't respond. I figured it should still be 'running' even without the GPU working, just without any display. This makes me worry there could be something else going on - or am I wrong?

I'd like to not have to worry my employer if I don't have to Knowing it's something Apple will replace would be helpful!

Yes, a GPU failure will prevent startup entirely.

 

[vdoeditdude]

Yes, a GPU failure will prevent startup entirely.

Maybeeeeeeeeee...........

Also look to your RAM. Try running with just one pieces, then swap for the other and try r
running again. That too maybeeeeeeee will yield some results

 

[ryguy92000]

iMac Meltdown!!

Ok so a brief refresher. iMacs are temperamental when they crash (beginning and end).

If the power button only yields a couple of poorly timed clicks from the OD and no other sounds then believe it or not but it could be your HD (stick with me my story gets better).

In our shop we have seen this a hand full of times and it continues to perplex me to this day. When you initiate a boot by way of the start button a hand full of things MUST happen in order. 1) The power supply receives a signal from the logic board to start up. 2) The power supply starts the HDD the ODD and the logic board. 3) Next comes the LCD.

If ANY one of those things gets interrupted the process is halted. The part I'm sensing your stuck on is the HDD spin up. By design this device is brought up first as it takes A LOT of power to bring up to speed from a dead stop and even more after being shut down. If the HDD has experienced any kind of mechanical failure it COULD cause the power supply to continue dumping power to the HDD in a vain effort to wake the sleeping beauty. BUT if the HDD is DOA then it will continue to boot the HDD and leave no power for the rest of the machine, effectively seizing boot and giving only a small amount of available current to the next device, the ODD. Which in turn can't start and only "clicks".

Regrettably the only way to test something like this is to open the machine, and take the hdd out. Not a task for someone without out computer hardware experience but if you feel brave, GOOD LUCK!!

 

[tyhoerr]

Thank you all so much for the splendid replies!

So I handed this one off to my employer a few weeks ago, and he had it taken in to an authorized Apple repair place.

I got it back yesterday. They had replaced the video card, which they assessed to be the issue.

Booted up and worked great all day. Then this morning, I was going to download chrome from their website, and whilst downloading, I played a video on their homepage. In the middle of the video, the iMac went black and was unresponsive. I held my breath and pressed the power button. Nothing.

Waited 30 min, unplugged. Plugged it back in at a different outlet - nothing. No fans, no sound, no power of any kind.

I'm most confused, because the video card seems to have fixed it for a bit anyway. So any further thoughts with this new information? I was thinking maybe overheating, but I'm not as qualified as some of you to place the blame

This iMac is becoming the bane of my existance!

 

[DeltaMac]

Overheating means that your iMac will shut itself off.
A cooldown time - a few minutes to a few hours - it should start again.
Try removing the power cord for a few seconds, then reinserting. I would also suggest that removing power means that you unplug anything that might have its own power, such as a printer, or external hard drive. Wait a few seconds, plug everything back in.
Try power again.

If you get nothing - no lights, no fans no beeps or any flashes on the screen, then likely you have a power supply failure - or the shop missed something, and it's time to take back for more tests.