Pink bars on imac


#1

My mid 2011 27 inch iMac screen just goes to a grey screen with five vertical galah pink bars on it.
It fails to complete boot, as far as I can tell, behind the bars you can see the Apple logo and the progress bar, it nearly completes and then it goes to a pale grey screen(without bars) and then self reboots after a while, with the cycle repeating. No log on screen is reached.

This happens whether I use the installed hard disc or an external thunderbolt drive as start up.

This iMac had its video card replaced under the recall years ago, but of course now is well outside any technical support. Any work around anybody can suggest?


#2

That would be another video card, without a doubt.

Wouldn’t happen to know how long ago it was by any chance? Just wondering if it could be within any extended consumer law coverage following the previous replacement. I can look it up if needed, if you wanted to PM across a serial number.

Otherwise it’s a tricky one to work around. I’ve heard about some affected users removing the GPU kexts from their OS install to prevent the video drivers from loading, using the video card as a frame buffer only, but don’t expect any visual effects or anything requiring video acceleration, which is unfortunately almost everything on a Mac these days outside of light web browsing, email and document editing, generally speaking.

There were more reliable cards available for that model iMac with performance as a trade off, such as the AMD Radeon HD 6770M 512MB. Some older Radeon 5000 (2010) series cards may also work but I haven’t tried it myself. Some users have managed to get later MXM cards from other manufacturers like Dell working in the iMac as well, albeit without brightness control or boot screens.


#3

Hmm, I can’t remember the last time it happened and Apple replaced it. I’ve PMed the serial number.Do you think Apple might be good to me?

I ran an Apple hardware test, it too over an hour and said everything is fine. I don’t know if it ever detects anything.

I looked on eBay and you can get the card for $230-$260 or so. Not that I want to open it up particularly.

Thing is I don’t want to buy a new one right now. I am hoping a new iMac or Mac mini comes out in March or so at the rumoured iPad event.