Display corruption: A software problem? (Please read & help troubleshoot!)

[eji]

Okay, this is bizarre. I was watching The Simpsons tonight in VLC when suddenly the screen developed these strange alternating bars.

At first I thought it was a hardware error. My iMac was fresh from the Apple repair shop for a replacement DVD burner and had been running for about two hours.

But see the images below. Those are screenshots. So I'm left suspecting that it's some crazy software glitch and not a hardware error. And the odder thing is: Some things display fine except for localized corruption. Look at that screenshot of John Stewart. Just his face is covered with these bars. Although this corruption covers the entire screen, sometimes windows aren't pixellated/blocky at all, they just have a bluish hue to them.

What gives? Can anyone guess as to what the problem might be? Have you ever seen anything like this?

I've already messed with calibration settings under System Prefs, running through all sorts of options (resolution, gamma, etc). I ran Onyx and cleaned all my caches. Then I reset the PRAM and SMU. I even left the iMac to cool off for about 20 minutes. Nothing works so far.

 

[Makosuke]

I found out the hard way that it is entirely possible for hardware problems to show up in screenshots.

If you're saying "What?", that was my reaction. However, it appears as if OSX pulls the screenshot directly from the display buffer (or something), such that if the graphics chip is screwing up (as opposed to just a bad cable, which of course wouldn't show up anywhere in software), it can very much show up in screenshots.

In my case, the 9800 in my G5 tower went out, and the severely glitchy graphics screenshotted glitches and all, but it was a hardware problem (and fixed when the card was replaced under warranty).

It's pretty easy to check; load up the hardware test disc and see if it shows up there (or, hopefully, if the test itself gives an error). If so, definitely hardware. If not, STILL has a chance of being hardware, but if it doesn't show up in the OS install disc either, then you'll probably have to do a fresh OSX install to be positive.

It was interesting in my case because only 3D things were glitchy; the simple draw routines in the test disc didn't show errors, and I could even clear them up by turning off accelerated 2D display via the developer tools, but since OSX uses a bunch of "3D" acceleration even just drawing the 2D interface, that was screwy. Even Apple agreed it was a hardware problem once I'd checked carefully, though.

Good luck, and hope it's just a software issue in your case.

 

[eji]

You're right, Makosuke. It's hardware. I ran the diagnostics off the install disc and VRAM came up with this error (which I could barely make out for the corruption):

ERROR CODE 2ATI/1/4 113-xxxxx-117

Coincidentally, I Googled it afterwards and found this MR thread.

Crap. Now it's back to AppleCare.

First the power supply failed last Feb, then the DVD burner a couple of weeks ago, then the VRAM last night. This isn't looking good. And AppleCare is set to expire later this year. Think I've got any chance of handing it back in and getting a discount on a new computer?

 

[SaSaSushi]

You're right, Makosuke. It's hardware. I ran the diagnostics off the install disc and VRAM came up with this error (which I could barely make out for the corruption):

ERROR CODE 2ATI/1/4 113-xxxxx-117

Coincidentally, I Googled it afterwards and found this MR thread.

Crap. Now it's back to AppleCare.

First the power supply failed last Feb, then the DVD burner a couple of weeks ago, then the VRAM last night. This isn't looking good. And AppleCare is set to expire later this year. Think I've got any chance of handing it back in and getting a discount on a new computer?

I've never heard of Apple offering "trade-in discounts"

That said definitely make a list of everything that you can possibly find wrong with the machine send it in to Applecare for service while you've still got time. The good news is you probably need a logic board replacement with the VRAM thing and it is better that it died now and not 6 weeks after your coverage ended like mine did on my last iMac. That ended up costing me $450. I bought AppleCare on my latest iMac.

I realize your machine is a G5 nearing the end of it's 3 years. A logic board replacement, if it comes to that, should be like basically getting a new machine. You've had a power supply and DVD drive replacement already so I think you'll be good for some time to come.

Good luck!

 

[loudandproud]

Makosuke, I'm experiencing the exact same problem with my Powermac G5 dual, and getting the same error code.
You wrote In my case, the 9800 in my G5 tower went out, and the severely glitchy graphics screenshotted glitches and all, but it was a hardware problem (and fixed when the card was replaced under warranty).

So replacing your AGP card for a new one solved your problem?

Thanks for the help!

 

[Makosuke]

So replacing your AGP card for a new one solved your problem?

Yep, instant fix, running fine for maybe a year and a half since. In fact, the replacement 9800 had one of the better, quieter fans (the early 9800s in G5s had incredibly whiny fans--it was noisier than all the other ones put together), so I was kind of glad it broke under warranty.

You could always get an extra-cheap card to test if you don't want to fork out for a higher-end graphics card only to find out the problem came from something else.