Red and green square dots?

After some interesting findings I discovered that powering down my iMac and later powering on a cold machine produces a ton of crashing/freezing/pixel glitches. Once the back of the iMac is very warm to the touch, I notice improved stability, I can actually get work done. So I've been leaving my machine running with all screen savers and sleep modes dissabled, running 24/7 as a result. Anyone notice this with their 2010 iMac?

Yes. I notice the same thing. When I first login when the iMac is "cold" (even if it has been powered on), there is lots of pixels flashing and instability. If I take it easy and let it warm up a bit, there is very little problem - even for long periods of time with lots of apps running. I'm not sure how consistently it behaves this way, but I do think that there is something to the "cold" vs. "warm" factor.

hmmm. Can we rule out software with this single behaviour or does a cold machine simply exacerbate it? I only ask because I'd be willing to go out on a limb and suggest that my machine might have faulty sensors, etc.

I still believe there's an underlying software issue if I can use Chrome just fine and can't touch Safari. Vice Versa for others. But if the hardware isn't communicating effectively with the OSX...

Browsers have nothing to do with it for me, as far as I can tell. I've had the erratic, crazy, unstable behavior without any apps open.

what about opening up the imac and removing as much dust buildup as possible? I had quite a bit of dust in my machine. removed the glass bezel, the LCD and used compressed air. I noticed less screen garbage...and slightly different pixel issues, like uniform lines that eventually dissapeared and migrated back to some random pixels--barring cold startups.

The more I report on the symptoms of my 27", the more I might have legitimate hardware/connection issues. Is there any solutions that can clean circuit boards and cable connections without damaging or corroding?

My mac is amazing clean (physically). If anything, a cold boot is when it works best (cold physically and operating state).

By rolling back to 10.6.7 I've only had minimal dots, and crashes only occur if it is left in sleep overnight (as opposed to just powering it down).

If it is hardware, can someone explain how hardware problems would produce the below images:

... notice how as I go through files, the dots are skewed and stick to the folder images. Also, in the last image, the dot is overlayed by a translucent scroll bar.

Our previous best proof that it was software related was seeing the blotches through remote log-in/screen sharing, but that is a spectacular find, Frudah! It looks like the icons have the measles. We need a cure for this!

...crazy. I obviously don't have an answer, but I'm blown away at the stability when my machine runs hot vs. cold.

I'm leaning toward hardware, but won't argue with driver/software issues--there's a lot of smart people on this thread.

I think Apple has likely seen some dusty machines. I don't smoke, no pets and I'm 8/10 for cleanliness and my 2010 imac's case was loaded with dust. Apple's probably looking at this and contributing heat/sensor and connection issues after x amount of operating hours, they're proabbly approching this from strictly the hardware side.

After blowing out the dust my machine's components, there's still a slight film. I want to try and remove this micro-level contaminant. I need a special cleaner or something. Would love to see how the machine runs after that...

One hardware possibility for this, is that these folder icons are stored in video ram and that ram is becoming corrupted. However, time after time, people are reporting 'genius' bar employees scanning their hardware and finding no issues. Sooo... what could corrupt ram other than hardware issues? Ummm... software?

I should've mentioned previously as well, that when the 'dots' have appeared previously, sometimes I'm able to put one of my application windows in front of them to hide them... as if they are only on the desktop. Moving the window away, will show the dots again, in the same place. Although, sometimes the dots are actually on the application window and move when the window is moved.

Also, still triple booting in to Kali Linux (Debian 7.3 derivative) and no issues with dots or crashes.

Issues in Windows 7, running bootcamp drivers 5.0.5033. BUT, never any issues when running full screen games that take control of the display interface. And, that is what I mainly do with my windows partition. Two minutes of logging on, I see dots. Hours of gameplay, no dots. No video issues.

see, here we go again with the opposite experience: I can wipe away my janky pixels by moving an app window. My pixel garbage is 95-99% on the desktop image. The app windows are doing fine- (--this being the lastest after blowing out the iMac with compressed air). Before I did this, pixel garbage everywhere, systemic in every app, no matter what OS was installed.

You clean out the case with positive air pressure, run the computer 24/7, boom, almost glitch-free.

EDIT: oh, also, Safari corrupted my system so bad I no longer open the app because it literally lit my screen up like a christmas tree. Using Chrome. ...Mac utilizing that questionable video ram for Safari much!!???

Chrome with this lemon iMac is a dream, almost don't realize I have a problem some days.

Sometimes when I move a window over the dots and then remove it, they are gone. That happens to me as well, but not as much as them being there still. My point was that the image is buffered somewhere and even upon re-rendering the screen, sometimes they are still there.

What OS's have you tried SoulNational?

I've tried every OS upgrade path that allows you to jump to Mavericks at the app store, currently using 10.9.1.

Originally, I had really bad symptoms during the time of Mavericks release and was hoping it would fix my iMac. It was the same after the upgrade, totally frustrated I was ready to pawn it for parts....

What I did was erased my hard drive, clean installed 10.6 and then upgraded. Before I downloaded my first upgrade jump, I noticed hard pixel distortion and really bad symptoms in 10.6. So I figured I had hardware issues. Ran the diag tool and everything was fine. (scratching my head at that point, and reading this novel of a thread)

Opened the iMac, removed the LCD and went to town with a filtered compressor & air nozzle. 30 minutes later I reassembled and the difference was "whoa".

Continued the jump to 10.9.1 and then isolated serious issues running Safari and my energy saving modes. Nixed those. Here I am now running failry smooth, hoping to keep this going for a few more months. Probably will dissasemble again and de-dust...

moral of the story: what I do externally to this machine makes a bigger impact than anything Apple has offered up in their upgrade suites. Sounds like it's a hardware issue---for me anyway. Would be awesome if I was wrong; that would save me $1K or more...

The last thing I'll add is that my iMac's symptoms gradually became worse over time. This was a buildup of glitches to a point where I couldn't take it any longer. I didn't have Apple Care, so I tolerated the increasing pixel junk.

I kinda attribute this to a buildup of dust over time. Some circuitry has probably overheated over the past 4 years and it's past the point of normal function. Luckily, I can isolate the offending apps and modes that trigger this machine's disease & relapse.

Maybe Apple's reading this and wants to offer me a job in their hardware design department. 🙂

www.jared-french.com

CHEERS.

Add me to the list, Mid 2010 27" 2.93 i7 iMac. Clean install of Mavericks didn't help, symptoms showed up immediately.

On "cold" starts it would get pretty bad and even freeze up so I would have to force it to shut off and restart. I would process a video in handbrake to get it to warm up and after 10 minutes or so it would go away.

I was given a 27" LED Cinema Display so I connected it to see if it would help. It's been 3 days and I've seen 6 squares and everything seems stable now.