iMac will not start up and stuck in reboot loop

Hi roofyro,

Did the new video card solve the problem with your iMac?

I have a late 2011 27" iMac with the exact same symptoms as you had (and tried all the same solutions, with the same results).

Thanks

Steve

My iMac (2011 27") just did the same thing. According to the App Store, it upgraded to the new Mac OS (which I told it not to do) a few days ago and now I'm getting the gray screen loop. I was able to boot off the DVD OS once and check the disc (said it was okay). It then restarted and I was able to get to my desktop. I tried copying some smaller files to my USB thumbdrive, but before it finished the copy, the screen went beige and restarted. Back to the loop. I was able to get to the desktop one more time, then launched TimeMachine to do a more current back-up and it went black. Now the issue is solid.

Marc

If the last four digits of your serial number is one of these

DHJQ, DHJW, DL8Q, DNGH, DNJ9, or DMW8

DPM1, DPM2, DPNV, DNY0, DRVP, DY6F, F610

I would bet my lunch that your AMD RADEON 6970M video card has failed. There is no repair worth doing other than replacing with a NEW card or a used working pull that has not failed - YET.

Larry

Larry,

I took this to the Apple Store last night and they ran a diagnostic. It was indeed the graphics card. A pricey replacement ($700) but they found the problem in less than 10 minutes. The tech told me this is a common problem with iMacs of this generation. It did last six years without issue and fixing it is much cheaper than a brand new computer.

Thanks,

Marc

There was actually a repair extension for this machine. They replaced these parts for free if you were within 4 years of the purchase date. While a lot of machines probably got fixt a large number of them managed to make it > 4 years before showing symptoms. And you had to have a failure before they would replace it. If your machine was functioning fine, even if it had a known defective part that was more likely to fail than not, they would not replace it. People like you and I and others are SOL. There is no (worthwhile) repair. Replace with new is costly but the only reliable solution. Those who claim they can bake it back to life or reball the chip are rolling the dice for you. Might last years, might last hours. Not worth it in my opinion.

First as a rule of thumb NEVER EVER upgrade the OS unless the computer is operating perfectly. All you do is make a situation more difficult to figure out.

Have you installed any:

1. Antivirus apps
2. Cleaning apps
3. Third party maintenance utilities

Please answer all three questions.

If you think you have a hardware problem, then answer is simple take the machine into be diagnosed by a professional. Someone that has the right tools to properly diagnose the computer. You can find an AASP in your area by clicking AASP Locator

My guess is the HD, however getting it professionally diagnosed is the only way to tell for sure. Otherwise you are throwing time and money into a guess. You can try to run Apple Diagnostics, Apple explains more about it in Using Apple Diagnostics - Apple Support

If the machine won't even run AD, to me it's more evidence of a hardware issue. You know what I recommend already.

this had happened to me, I took it into the apple store and they told me a file was missing, we restored to store purchases and was good from there. (till it happened a few months later, but never again)

I would guess the issue is not as likely to be hard drive related, which leaves...?

- logic board?

- power supply?

Yep. Both of which are extremely expensive. What are you going to do?