Flicker/Blackout/Unresponsive

Maybe someone can relate.

I'm on a 24", Early 2008 iMac, 6GB ram, NVIDIA GeForce 8800 GS 512mb and running OS X 10.9.2 and on Monday something really weird happened...

I'm using the computer, browsing, etc, I get up and walk away from it and upon coming back to it, the screen was "dark" It almost seemed like the back-light went 100% off. Not the same type of darkness as putting the screen to sleep or anything. Computer was completely unresponsive, yet, on with the drive spinning. No strange noises. Clicking of the mouse yielded nothing positive or beneficial, so...

I did a hard shutdown, restarted, and everything was fine for the rest of the night.

Then today,

(Tuesday) I'm on the computer and randomly out of the blue the screen dimmed/flickered slightly, and within seconds, I got the same dark screen. I tapped the enclosure but that didn't help. I fiddled the cable in the back that's hooked up to an external TV as a second display and all of a sudden the screen on the iMac came back. Coincidence? Who knows. However, the computer was completely unresponsive. Mouse movements, key bashing does/did nothing.

Next up, did a hard shutdown, unplugged the iMac cord, let it sit for a couple minutes before running a 1.5 hour Apple hardware test. Everything came back FINE.

Couple of interesting points:

I've never used the USTREAM site in the past until this Monday. Both these screen blackouts happened when I had USTREAM streaming video in Firefox. Could this be related to something on that website? Flash based? I wonder?

I use Photoshop/Lightroom and frequently play videos on here (YouTube specifically) no issues with ANY of those applications/sites even on the heaviest load.

I haven't found that many GPU crash results on google from the use of Ustream, but I have found some related to general Flash based applications and videos.

Kernal panics usually result in a complete shut down (in my experience). This was limited to no warning at all, just flickering slightly followed by a dark screen and a completely unresponsive computer.

What could of happened here?

I sure hope not. Everything was fine until trying that site.. I really hope it was just that site.

Console has popped up: NVDA(OpenGL): Channel timeout!

each time after the lockup/crash.

Update: screen issues

No issues from Wednesday-Friday. Then today (Saturday) upon starting the iMac to watch something on the tv (via iMac) the TV was flickering and loosing connection to the the iMac. The connection is HDMI, so upon unplugging it the T.V lost connection (understandingly) but the iMac got some STRANGE white glitch lines running from top to bottom, spazzing out, etc.

Then it did its usual light flickering and went black and unresponsive. The screen was back-lit slightly and stayed on, but everything was dark. Did a hard shut down and upon starting up again the screen wasn't back lit, instead, it was fully black aka, dead.

Graphics card officially done? or Mobo issues?

I haven't bothered with SMC or PRAM resets, never had issues with this computer really in the past. First time has happened.

This is probably unfix-able, being that Apple or any stores don't stock video cards that old (to my knowledge at least)

Anyone here have any ideas? Or should I just remove the hard-drive and trash the 2008 beast?

I added new ram last year, specially for Macs. Haven't had any issues with it and it passed several tests upon install and use. This has to be graphics related

The card is the infamous 8800 GS, which lasted, 6 years to the date... perhaps I'm asking for too much, but I'd expect a graphics card to last a little longer then 6 years. Good cooling here, cpu never went higher then 50c on high loads, fans never went nuts, I installed a new hard drive just over a year ago and the machine looked CLEAN inside, barely any dust anywhere to be found.

If this turns out to be a graphics issues I don't think I have any choice really but to chuck it. Which is a shame because other than this issue the machine is FAST despite the fact its from 2008.

Well the RAM and HDD is in new condition basically. Everything else is pretty much fine too. I'll remove the ram and hard drive, keep the keyboard, mouse (which still works fine) and the rest will just go to the dump or get recycled.

Back to windows for me. This ain't gonna be fun... lol

I wonder if the MAC keyboard will work with windows. I love that design. Should work I suppose besides a few keys not functional.

matreya said:

Before disassembling the iMac I would try disconnecting the 2nd monitor and seeing if that helps...

Click to expand...

Unfortunately that didn't yield any benefits in the past. Now when I turn it on the screen is completely black, so I had to hold the power button in the back which put it back to sleep. I'll awake it in a few hours to see if I can see the screen and desktop, other wise I'll have to access it via Firewire from my Macbook and then see where to take it next. Really wish I could fix it before chucking it.

I think the logic board is fried. The keyboard is complete unresponsive to the system, the chime upon starting up is there but its just a black screen after.

I tried to boot it up in Target Disk Mode using my MBP and it didn't recognize it. Nothing came up on the Macbook. So unless I'm wrong, the whole iMac board is fried, hence why the keyboard inputs and firewire inputs aren't recognized even. I just read on google that if the mac isn't starting up in Target Disk Mode, then its mostly like dead.