Red and green square dots?

A hint, perhaps it is not the case for everyone, but ... it might be a failing system hard drive!

I find it hard to believe, too, but try this... (It will not fix your system, but it might save you some money)

I have had the same issues like the user here:

https://discussions.apple.com/thread/4825519?start=0&tstart=0

Like for many of you, the hardware check went along fine. But now I know better not to rely on it again.

Anyway, i wanted to reinstall the system, just to see if it could help any before paying a mountain of money to Apple "geniuses". It didn't work, could not boot from cd no matter what. Only "safe mode" and "single user mode" were accessible. So, i went to check the drive using single user mode. If you don't know how to do that, go here, and follow carefully the instructions for: "Boot Into Single User Mode"

http://macs.about.com/od/faq1/f/emergencystart.htm

Follow the instructions closely, especially the part with repeating the fsck command!

In my case, i had to do it a couple of times until the message "FILE SYSTEM WAS MODIFIED" went away.

After the boot... Lo and behold, no stripes, and mac boots up into standard mode!

Sadly, this will not fix anything. After some time, the artifacts started showing up again, and crash occurred.

But, at least I have my suspect! :)

And, the results using this method are repeatable and consistent.

So, to conclude, to me all the symptoms so far support Hard drive damage. To recap:

- Removing data helps some because there is less chance that system will hit the bad sector.

- Removing startup items, (that are cached on the disk) helps others.

- Using less apps that make big swap files helps some, too...

- Changing gfx and logic boards did not alleviate the problem. (Because the disk is the issue?)

Now, some of you did exchange your drives. Hm. I don't have idea here...

Perhaps the new drives were faulty? Perhaps the drive image copied was faulty, too?

Perhaps it was really the gfx or logic board?

... in my case, you people were probably right, it is not the graphics hardware! But, again, it is hardware ;) hard drive!

There. i will try to replace the hdd when i catch some time. Probably cheaper than letting "geniuses" fix it.

I HOPE this can save us some money...

... I have just realized that Mr. Tom Nelson from about.com was the key person in solving so many Mac issues for me! I should let him know I'm grateful! :)

I suspect it as well. There has been one success and another who said the drive swap didn't help. dgd2000, have your dots stayed gone after the new drive was installed?

jmf

Droid Alex wrote:

A hint, perhaps it is not the case for everyone, but ... it might be a failing system hard drive!

I find it hard to believe, too, but try this... (It will not fix your system, but it might save you some money)

So far, everything is working fine after the hard drive replacement a month ago.

The old drive was a Seagate Barracuda 7200 1TB drive, S/N: 9VPGHC0X, date code 13143. It would be interesting to see if others have the same model drive from the same manufacturing batch... Of course, this WAS a replacement drive that Apple installed in late 2012. The original one started making noise, but never failed completely and I never had any video issues until several months after the replacement drive was installed.

I'll let you folks know when my green and red squares return (as you can tell, I have little confidence that my system is "cured.")

Hi, I'm writing from Mexico, my iMac had the same behavior as described earlier on this tread, (exact same problem) everything was working flawless until a few weeks a go when all of a sudden my computer freezes with the coloured squares showing on the screen, it was solved temporaly by rebooting but it only last about 1 hour and it happened again, since then the computer starts ok but after a few minutes it freezes again so it's impossible to work. My iMac model is also (11,1) 27-inch, Late 2009 Processor: 2.6 ghz Inter Core i5 with 8gb of ram, Graphics ATI Radeon HD 4850 512MB Serial Number: W80100P85PJ, at the time of the first incident I was running Mavericks, after following this tread for about three weeks I decide to open it since it is no longer on warranty and I remove all the dust with compressed air cans and also I change the hard disk for a new Seagate 3TB just in case it was hd failure as some suggested, I did a clean instal from the recovery disks that came with my computer when I bought it, it was Snow Leopard and everything was ok BUT since I wanted to test the video card I downloaded and istalled Chrome and went to Youtube and played a video playlist and it took only three videos for the computer to freez again. So as a last attempt I'm exploring the browser theory, specially the Chrome theory, so I uninstall Chrome and restart since that it's been about 3 hours of working and still no problems (fingers crossed), I'm going to install Final Cut Studio 3 and edit videos for some hours and I'll report back.

Greetings

TL,

You summed up nicely this thread. Keep us posted.

I have my computer working by decreasing resolution. I world also recommend cleaning up the junk software with AppCleaner, Uninstll PKG, LaunchControl and EtreCheck.

jmf

I brought my mid 2010 iMac in for repair, here is the quote:

I am hoping it is just the video card. If the card gets replaced and the problem persists, I'll likely just flip the computer. For clarification, the specs on my iMac are as follows:

Mid 2010 27" iMac

OS X 10.9.1

2.8 GHz Intel Core i5 Quad Core

24 GB 1333 MHz DDR3 Aftermarket RAM

ATI Radeon HD 5750 1024 MB Graphics Card

240 GB Intel SSD (replaced original 1TB through recall)

Will update with the results after repair is made.

Hi, I have somewhat good news. In short, I have re-flowed (spelling?) my video card a couple of days ago and iMac is working as good as new.

So, to reiterate, my previous suspect - the hard drive, was not the issue, although it was a strong suspect. After scanning the HDD using another Mac, formatting it and scanning again, there were no signs of hard drive damage. The reflowing of the video card was done at home, in the oven. The only cost being the time to learn the theory behind re-flowing, a few hours of getting familiar with iMac, the cost of electricity and a small tube of thermal compound, totalling about 10$, I think. At this moment, iMac is behaving beautifully, running fresh Mavericks. Just in case, I am monitoring the temperatures inside. 3d benchmark executes nicely. So far, so good.

If you would like to go this way, and do not know about re-flowing at home, be warned that it involves some relatively complex disassembly of your iMac, and a possibility to break something inside if you are not careful enough. My suggestion would be to get familiar with the theory behind re-flowing first and foremost. Wiki and Youtube will give you more than enough information for this particular application. Also, prepare yourself about the insides of your iMac. Other than that, you will need only the basic tools, and a lot of careful effort. My iMac was out of warranty and the service costs would have been very high anyways, so I decided to give this approach a shot. It worked. If you have any questions about the details of this process, of course, after you research online ;), please let me know. Since this is not my thread, and it might be irrelevant to other users here, we can start a new thread considering this.

Alex, Keep us updated after a few weeks to see if reflowing the video board is still working. It is certainly the most extreme idea yet, but makes some decent sense. Ripping apart your computer and baking parts in your oven is definitely not for the average person, but I reflow boards at work so I'm familiar (and we actually use a toaster oven!)

Unfortunately thought this would be the same as getting a new replacement video card which we have seen plenty of reports of not working. So let us know in the long run if it continues to work for you.

Of course.
On a nerd side, purely as a curiosity, to those interested: you might be surprised to know that the fit between the heatsink and the memory chips on the card is very poor. Up to 1mm of gap. The fit between the GPU and the heatsink is fine, which is what matters the most. But, probably to compensate for that memory chips gap, they have put overly copious amount of thermal compound there and on the GPU! The result was: drying out of the compound over the years, which created cracks and airgaps, drastically reducing the ability to cool the card. A lot of thermal compound spilled over which, without a cooling body to transfer the heat to, additionaly acted as an insulator and contributed to the card's overheating.

I got mine back from apple on 1/20/2014 with a long over due repair. Now am getting my dots back and video all scrambled and random shut downs since then. Here is what they done.

SVC,VIDEO,ATI.RADEON.HD.5670,512.GDDR3

Part.Number:.661-5578

Item.Warranty.Code:.OW

No.Returns

APPLECARE.SUPPORT.www.apple.com/support/

$.Off.Customer.Service

SVC,CABLE,SD.CARD

Part.Number:.922-9265

Item.Warranty.Code:.OW

No.Returns

APPLECARE.SUPPORT.www.apple.com/support/

Hardware.Repair.Labor

Part.Number:.S1490LL/A

Item.Warranty.Code:.OW

No.Returns

Am hesitatnt to bring it back since its a hassle. And this wan't replaced for free with no recall on mid 2010. The recalls are on the 2011.

What I do notice is that I leave my imac i5 on all night then I wake it up from sleep and all the issues happen.

On my other imac 21 I have no issues since its a mid 2011.

Apple knews about the issues and did nothing for the mid 2010 and recalled for 2011 only. Shame on Apple.

Still having issues with replacements. Apple what the F.... Rip off loyalty customers. My only major issue with macs since my quadra back in 1996. lol. Cant really complain just frustrated.

I started having the same problem after installing Mavericks on my mid-2010 iMac, 2.93 i7 with the 5750 card. It's never really gotten worse but I finally decided to try and figure out what's going on, especially now that my AppleCare is expired. I'm also wondering if this may be a software issue due to:

- The pixels are never showing up for me on the login screen, AHT screen, or when using the display in Target Display Mode

- AHT is coming back with no errors after running it over and over for a 24 hour period

- I erased and repartitioned the drive and never had pixel issues during install or setup

As soon as I got back up and running on Mavericks with no programs installed other than the core OS, the green and red pixels came back in the Finder within a minute of boot. As a last ditch effort I installed Mountain Lion to an external drive tonight and have the iMac booted to it - and so far after two and a half hours, no pixel issues. Could there be something in Mavericks killing the graphics I'm the older system (not that 3.5 years is that old when it was the top of the line and still compares well in specs!) 10.9.2 doesn't appear to fix it either, so maybe I'll got back to 10.8 and monitor it to see if the problem reappears.

Look what happen this morning. This is all new this blue screen. So I left it on last night in sleep mode. I come back in the morning and pixels come out. So I restart and get flickering blue screens. Restarted the computer a few times seems to be working fine for now. Time to call apple and bring back the computer and see whats going on since they just gave me a new video card. Hassle....

Message was edited by: harrisny

harrisny wrote:

Look what happen this morning. This is all new this blue screen. So I left it on last night in sleep mode. I come back in the morning and pixels come out. So I restart and get flickering blue screens. Restarted the computer a few times seems to be working fine for now. Time to call apple and bring back the computer and see whats going on since they just gave me a new video card. Hassle....

Message was edited by: harrisny

yep...you have to leave it on 24/7 keep it warm or those symptoms are exacerbated when it runs cold. Disable your sleep and energy saving modes.

On a side note, my Chrome broswer is linked to hard freezes now. Thought I had it isolated by not using Safari. Now, I reset my iMac probably 10-15x per day. Out of sheer laziness and stubborn hard-headed expactation for these machines to run well, I haven't done anything about it yet, because going down that road chews up a full day of my time and no guarantees to curb the symptoms at most.

Next venture is swapping the hard drive. Could, might help we'll see.

They replaced my HD for free a year ago because they had a recall program for the mid-10s.

https://www.apple.com/support/imac-harddrive/

hmm. Intresting. But my OS drive is a 512gb flash storage form a custom built CTO they rejected my serial #