Q: Red and green square dots?

Not sure if that one should be on the top rack or bottom,

since Target Disk Mode is a very limited aspect of OS X

and does not represent an adequate test of the Graphics.

Oh, be sure to bake those cookies first while warming

the oven, and double-check any temperatures.

While there are some ideas on baking graphic cards,

I did not look into the iMac logic board receipes yet.

This summer, depending on how things work out, you

could just set the whole works in the barbeque... LOL

Neighbors may see the smoke & set-off an alarm, tho.

Life is too precious to take it serious.

Good luck & happy computing!

Quick update on my 2010 27" iMac... Genius Bar took it for repair, intending to replace the graphics card. However, they saw that I had an Apple Certified tech install a third-party SSD. They complained that the SSD was too close to the graphics card, which could be causing my problem. So, I took it back to the Apple Certified tech who checked it. He said that the SSD is exactly where it is supposed to be. But he took it apart, cleaned it out and put it back together. He ran all the diagnostics and tested it for 24 hours and couldn't reproduce the problems I've been experiencing. As soon as I booted up the iMac at home, the screen distortion apppeared. I've been having trouble ever since.

I'm super frustrated.

I know that some have had success using the defective iMac as a secondary display for another computer.

Has anyone tried using connecting a monitor to the defective iMac? If so, does the graphics distoration (as well as freezes) occur when using a connected display?

My mid-2010 27" iMac has been experiencing similar "shimmering" or "dancing" pixel - mostly, in the morning after mysterious over-night restarts of an unknown origin.

Mavericks (latest iteration - 10.9.2 - which wreaked considerable havoc, initially) - Chrome as primary browser.

Concerned that my display may be failing, I first ran Apple's Disk Utility to repair permissions on the internal 2Gb Seagate hard drive, and "voilå" - shimmering vanishes!

This morning, the only repairs effected were:

Group differs on “Library/Printers/InstalledPrinters.plist”; should be 80; group is 0.
Permissions differ on “Library/Printers/InstalledPrinters.plist”; should be -rw-rw-rw- ; they are -rw-r--r-- .
Repaired “Library/Printers/InstalledPrinters.plist"

Have absolutely NO idea why running Disk Utility resolves this issue, but it seems to -  each and every time: Should I take comfort from the thought that it's NOT a hardware issue, or might this simply be a false hope on my part?

These issues - the occasional freezing, overnight self-restarts, and shimmering pixels - have only seemed to appear post-Mavericks: Anything to that, or mere coincidence?

Thanks!

My iMac was repaired by an Authorized Service Technician since Apple refused to touch my iMac. Swapping the video card seems to have resolved the issue for now. I will post if it comes back up.

Rudy C. wrote:

 

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.

Frudah...  39 months ago, my 24" imac started foing this...  I spent a lot of money replacing the GPU etc and it never helped...

so I gave that maching to friends that couldn't afford a mac after clean installing from scratch and rolling back the OS several versions (the problem went away).

Today, I am here with an iMac 11,3 and I got the defect two weeks after my applecare expired...  It's deja vous all over again for me.

I am convinced this is software this time.  I have my mac in safe boot right now, and there's no glitches, but it's annoying knowing I have to criple this machine to make it work as it should...

I am positive this is a defect in the OS...   but with my past, my other alternative is that it's a defect that triggers when applceare expires.  Between those two options, I'll say it's a bug in mavericks.

TDM doesn't use the possibly bad graphics card.

the response earlier where the guy ran windows in boot camp AND linux without glitches on the same machine sort of seals the deal that this is an OS issue (and not the hardware)...

I think perhaps they just don't update our graphics drivers anymore and yet ask it to do all this acceleration stuff probably with bad commands that make the VRAM leaky

P.S. -- safe boot prevents the glitches from appearing.

I wonder if anyone else has tried this.   Seems to me that if the hardware was a problem, then safe boot would not work either...  low and behold, I've read this whole thread and replied many times while mine is in safe boot and I've not had the green dots or anything...

So this probably means your newer Mac could run an older OS X

under Parallels, such as the server version of Snow Leopard.

Shades of 'back to the future' sort of.

Good luck & happy computing!

Hi, Ivan and everyone else...

This thread became a little bit too long, but if you have some time, you can find out about the efforts of others trying to determine this problem. The artifacts can seem to disappear in the safe mode because the safe mode is running only the most basic setup. The advanced kernel extensions (audio, graphics, etc) are not loaded and the gpu is running in its most basic, low level mode, too.

As you know, the hardware behind all of this is immensely complex, and the cold solder joints commonly develop in electronics that have considerable thermal amplitudes (such as the graphics card). When running in the safe mode, your card might not even use the pins that have developed the cold solder joints. And everything seems fine. But it is not. These two factors, (reduced demands on the software side in the safe mode and the difficulty in pinpointing the cold solder joints) make diagnostics especially difficult, and in my case it made sense to re-flow my cardto eliminate one.

In my case, re-flowing the card fixed the issue. I have left some links to theory and practice of re-flowing here and on some other threads. If you are to go that way, make absolutely sure that your OS is in working order and that your issues are very much like the screenshots kind people left around here. If yes, prepare yourself for relatively complex disassembly of your machine and also, learning some theory. It is not rocket science, but it is a serious undertaking that is extremely cheap and successful if done right. Good luck.

Also, as I promised a couple of weeks ago to this thread, i am reporting that my oven-baked ati 4850 graphics card is still working fine and no artifacts re-appeared.

I regret to report that my red and green square problem has returned. Here is what I said exactly one month ago today:

--------

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.")

---------------

It has been 2 months since my hard drive was replaced, which seemed to cure the problem - for a while. Last week the red and green squares returned again. I have NEVER installed Mavericks, so I am not convinced the OS has anything to do with the problem (I've seen this with Snow Leopard and now Mountain Lion on this machine). The problem is very intermittent; it will be there one day but not the next. I can't afford to throw away a 3+ year old machine, and I'm not sure I'll ever buy another Mac after this headache. I'll keep watching this forum (and my beloved red and green flickering squares) until someone provides a solution. In the meantime, I'm seriously considering going back to the PC world...

Thank you droid Alex!

That's a great summary.   I'm confused, though.   Why would the people who put a brand new GPU not get relief then, too?

I'm glad you solved the problem for your machine.  I want to solve mine.  For me, it makes more sense to get the $200 card and slap it in there, but the people who had that done at the store report they have artifacts.

What a mess!

I don't understand all the cold solder you mention.  Wouldn't that be fine on a new card?

-Why would the people who put a brand new GPU not get relief then, too?

As far as I know, and that might not be the whole image here, in some cases the problem might be the logic board, or even the oxidation on the contacts of the graphics card (as low-tech as it sounds), or the boot sector of the HDD might be failing, the screen itself might be failing, too. Also, some hardware installs less than well-made kernel extensions that can cause the issues with some other extensions. etc...

Most of these suspects you can eliminate through diagnostics. Unfortunately, the Apple hardware tests are not the ultimate word on this. Read this thread, people here suggested quite a few tests you can do on your own, if you want to. E.g. using your Mac as a secondary monitor, reinstalling the OS, checking whether the artifacts are present on the screenshots, too... etc.

I have been looking for a new card, too. Since the card in my late 2009 iMac is not made anymore, I could only get a used one. The price tag being very high, with my own card seemingly dead, and, hearing from the more experienced engineers that the used ones are most probably re-flowed, too... I did not want to go to the "Geniuses" because not a single time so far a "Genius" was able or skilled enough to fix the issues I had with my other Apple hardware (or software). I will spare you the rant on those guys and girls. So, I thought: what the heck, I cannot lose anything. Afterall, insides of a Mac is just another piece of electronics. Nothing magical in there. I learned about the background of the problem and did it.

My honest advice would be that if you can get a new card for an acceptable price, replaced by an authorized or experienced service and perhaps with some warranty, do that. Do not take risks.

Simplified, a cold solder joint is a soldered point which due some circumstances has developed cracks. These cracks, of couse, break the flow of the electric current and the contact is lost. Since those cracks are usually microscopic, and since there are hundreds of possible locations where they can occur, the whole electronic part (in this case the graphic card) is taken out of your computer, carefully prepared for heating and then heated to ~205C and kept at that temperature for some time. This makes the solder become liquid again and the cracks are mended. After cooling, the card is reassembled and used. This is an overly simplified description. If anyone is interested further into this, check the wikipedia, check the youtube. Give yourself a couple of days and learn. I am not writing the details here because there are much, much better sources of information on this topic already around. (of course, if you are doing this, do it on your own responsibility)

Droid Alex...  thanks for your summary and help.  I found a new replacement 661-5578 part for my imac only $220 and it even has the 90day warranty, I jumped on that, ordered it, and so now I need only to wait for fedex. 

In my past imac experience, this is going to happen again because my past 24" imac did this, so I figure having a backup card is worth it.

If I sell the thing later, it will be a bonus with it.  it's a BTO i7 with 1 TB HD and 480GB SSD and 24GB RAM...  it's a beast.   So, having this extra card sitting around that can be baked is good insurance.

wish me luck that this fixes it for me! 

Good luck with that Ivan!

If it is a graphics card cold shoulder problem or even a main board problem does anyone know why I cant get the artifacts to appears in bootcamp Windows 7? There is no less graphics intensity

I can also see the flashing square patches when teamviewered into my machine. Surely that rules out graphics card, right?

I am running windows 7 in bootcamp and am still getting the flashing square dots. It didn't at first, but now it will start as soon as I log in. However, I have noticed that the problem is the worst when the computer is cold (either coming out of sleep mode or just starting up).