Some users reported success, others said the problem persisted. Some owners claimed they were told a second fix would be available in February, and that turned out to be correct.
Apple has now released the 27-inch iMac Display Firmware Update 1.0 "to address issues that may cause intermittent display flickering."
It appears that the issue may have more than one underlying cause. Apple's notes on the latest update imply that it may fix some cases of flickering on its own, while in others the Graphics Firmware Update may also be needed.
"If you are still having display issues after successfully completing both firmware updates, contact AppleCare or an Apple Authorized Service Provider," advises Apple.
But can the problem really be fixed through software? Please read on.
TWire twice asked Apple whether 27in iMac production had been halted, but a company spokesperson would only say "the new 27-inch iMac has been a big hit with customers" and "we are currently estimating units to ship within three weeks" rather than answering the question.
There has been speculation that not all of the screen issues reported on current iMacs can be fixed through software, and that a hardware change (repair/exchange) will be necessary.