Problems with MAC (little pink andgreen Squares)

**ant3b** · 22nd October 2014

Hello,

I have an Imac mid 2011 with an ati radeon hd 6770m.

Just recentley I have been getting random pink and green squares.

If I go over them with the mouse the mouse covers them as if they are in the background. I also tried taking a screenshot and they do not appear?

Any ideas? if I position the windows in certain places more appear?

It is baffling me.

The mac has not crashed once in 3 years and has been working fine

**EvilBoB** · 22nd October 2014

Sounds like a GPU issue. Overheating or something. Corruption of GPU memory etc. Had a similar problem with an ATi card in my PC few years back. Bear in mind that when you take a screenshot it's taking a screenshot of what "should" be on the screen ie. before it gets sent to the gfx card to render.

You can upgrade the gfx card in the 2011 iMac according to this thread : http://forums.macrumors.com/showthread.php?t=1596614 that may solve the issue...

**Jokah** · 22nd October 2014

Certainly sounds like GPU instability to me.

First of all I would download a program that will let you monitor the GPU's temperature. I've never used a MAC so can't recommend a program but a quick google search brought this up: http://download.cnet.com/Temperature...4_4-41089.html. Somewhere within that program you will be able to read off the GPU's temp.

Your problem could be soemthing as simple as a build up of dust preventing it from cooling properly. If you do manage to find out what temp your card is running at let us know and we can advise from there.

**blacksheep** · 22nd October 2014

With above guys either overheating, memory corruption or not enough power.

**ant3b** · 23rd October 2014

Its not overheating .. t could well be dust... how would i clean the mac not easy to get into

and yes yuo can upgrade them but the cards cost a pretty penny haha.

I have never pushed the limits of the mac. Only use it for TV and movies the occasional browse of the net.. It has not been turned off for 2 years though apart from a reboot or 2 to update

**supraman54** · 23rd October 2014

Found this..

https://discussions.apple.com/thread/3699781?tstart=0

supe

**rebrabuk** · 30th October 2014

The 6770 GPU is a relatively cheap part to replace in the 2011 iMac models.

You could upgrade to the 6970 1GB or 2GB GPU, but costs would increase dramatically as the part would have to be priced and replaced as a stock item, rather than being priced and replaced on an exchange basis, as the existing 6770 card could be.

**EvilBoB** · 21st November 2014

Have you had any joy on getting this sorted?

**ant3b** · 21st November 2014

It seems to have stopped for the time being? no idea why?

**ant3b** · 21st November 2014

Originally Posted by rebrabuk

The 6770 GPU is a relatively cheap part to replace in the 2011 iMac models.

You could upgrade to the 6970 1GB or 2GB GPU, but costs would increase dramatically as the part would have to be priced and replaced as a stock item, rather than being priced and replaced on an exchange basis, as the existing 6770 card could be.

Please elaborate on the exchange option

**rebrabuk** · 21st November 2014

Originally Posted by ant3b

Please elaborate on the exchange option

Basically Apple offer 2 different prices for their service parts; a stock price and an exchange price.

- The exchange price can be offered when a repair is carried out and a like for like part is supplied/replaced, with the faulty part returned to Apple.
- The stock price is applicable when a repair is carried out but a like for like faulty part is not available to be returned to Apple (as in the case of a customer wanting an upgrade, or wanting to keep the faulty part).

If you want to PM me with your iMac serial number, i can provide the costs of the replace card to you, as offered by Apple.