Q: Red and green square dots?

Apple Hard Test - basic and extended pass with out probems

My iMac is still working a month after the video card was replaced by a local independent Mac store that is an Authorized Mac Repair Center.

When they were troubleshooting the issue, the problem was not detected by the Apple Hardware Tests, although it was very visible to the tech, as there were screen anomalies showing up even while running the tests.

I was skeptical about replacing the hardware, but so far it appears to have resolved my problem (knock on wood)!

3rd day after Mavericks update, still working.

(my boot screen was always perfect)

How many of us who are running the 32 bit kernel see the dots? It seems that the machines most effected are those where the 64 bit kernel is an option. The newer iMacs are setup by default to run 64 bit. To check, select Safari in the Applications folder and click on "Get Info." If you see 34 bit as an option your machine is running the 64 bit kernel. If you do not see the 32 bit option you are running a 32 bit kernel.

jmf

After checking Safari, I have the "open in 32 bit mode option".

That means your OSX is using the 64 bit kernel. And you have the square dots? Have you found anything that reduces the occurence of the square dots?

It is mostly problematic on a cold boot. Waking up in the morning and turning on system produces so many squares that I can't see the login boxes. A hard reboot reduces the dots by 80%.

To fix the remaining dots, I can usually erase them by dragging a window over the dots to reduce to 2-5% coverage. The dots seem to be related to the graphics card switching when using adobe products or any program that uses the AMD Radeon HD 6750M 512 MB card, but I can't say that is 100% accurate. 

The latest update to 10.9.3 did reduce the occurrence by a fraction, but did not rectify the problem.

Add me to the list.....   I've been dealing with this issue for over a year now.  Mine is a Mid 2010 27" iMac (2.93 GHz i7) with the ATI Radeon 5750.  I'm on OS 10.9.3.  It started gradually at first and got progressively worse as time went on.  I took it to the apple store and paid them to replace the Video card.  This appeared to correct the issue for a while but eventually the problem returned and the video card was replaced a second time.  Again the issue subsided for a about 30-40 days and then started reappearing small at first.  Its getting prgoressively worse again. Eventaully I will encounter a 'garbled' screen (see below).  The only way out of this is to reboot with the power button.  After reboot it's back to normal.    I think its interesting that many of my desktop icons are not impacted when this garbled screen happens.  Not sure if there is any significance to it.   Unfortunatly I don't have any pictures of the small red and green squares that i encounter 99% of the time.   The screen below is the 1% extreme that occurs as the situation gets worse. 

The Apple store has said they would replace the card again but i would also need to replace the 'motherboard'?  I hate to buy a new one as when i buy i tend to 'max out' the options with the intent of using it for several years.   At this point i'm tempted to return to Windows.  I justified the premium price of a mac to avoid things like this plaguing me.   Also, I can't say that i've noticed it occuring more frequently at 'startup' or cold, but it could.

esure

cPro,

They replaced the video card, but did they replace the heatsink?

To me, this is all a hardware problem.

Dendrites

Whiskers

Thermal fatigue/cracks

Bad heat pipes

Dust

Low quality TIM/crappy application of said TIM

Warped heatsink faces (see "bad heat pipes" above)

And lastly,

My Personal Favorite,

Did they replace the frikkin' 4-year old battery?

R

BTW, my son's iMac has been running 24X7 since May 5th without a hiccup.

Count me "lucky", but my mid-2010 27" 2.8 i5 hasn't experienced a single recurrance, since I changed sleep settings to "never" for both hard drive and monitor - regardless of subsequent OS upgrades (now at 10.9.3):

Just running a screen saver with a desktop picture when in use...

Same here....I changed the sleep settings to "never" and only use the screensaver and have not had an issue since then...

OK... so I updated to 10.9.3 on the 17th but was out of town for the a couple days so my Mac just slept. I've been using it the last couple of days and am now noticing the pink squares. Actually, as I type this, the squares are popping up here and there. Mostly on along the top of Chrome nav bar but sometimes along the middle of my screen. No lock ups yet though which is something.

The squares actually flash on and off....

So as I was typing the message above, my **** froze up again. So there goes the hope that the update fixed this **** problem. So frustrated with this.

Gonna try removing all energy saving options to see if that reduces the problem like it did for some of you.

Citiboy/Kuzy  I tried your suggestion and i thought maybe it might work becuase i had several days with minimal flickering.. but this morning they are back with a vengeance.  Nothing else has changes on my system.  So back to square one for me......  Today my machine actually did a restart on its own.  I came out of screensaver.. noticed the dots.. then a gray screen and restart. 

Turn off screensaver, and never sleep.