updated 05:45 pm EDT, Mon August 19, 2013
AMD Radeon HD 6970M video cards said to run exceptionally hot, fail early
Users who have a 27-inch "Mid 2011" iMac, which was sold between May of 2011 and October of 2012, may have a failure-prone video card that might need replacing, Apple has revealed. The company has started an official program to replace cards that have failed or are failing on iMacs up to three years after the initial purchase, even if the customer's original warranty has expired. Only select models of the 27-inch iMac with the AMD Radeon HD 6970M cards are affected, and customers who have already paid for repairs can be compensated.
The defective cards can cause video distortions, described as "white or blue with vertical lines" in an Apple support document, or may just fail outright -- resulting in a black screen but indications that the computer is otherwise working fine. The specific models affected are the "Mid 2011" 27-inch iMacs with 3.1GHz quad-core Intel Core i5 processors, or those with 3.4GHz quad-core Intel Core i7 processors, both of which came standard with the AMD Radeon HD 6970M cards.
Some users with affected machines claim the problem stems from Apple's use of lead-free solder in the assembly of the machine, which they say is not as resilient to heat as leaded-solder. However, Apple has had a number of video-card issues related to soldering over the years (most notoriously the iBook G3 and G4 models) long before it began using lead-free solder. Furthermore, iMacs which don't have the AMD Radeon HD 6970M card don't appear to be affected by the issue.
In order to qualify for a free replacement, the existing machine must be showing signs of issues. Users who are not experiencing issues will have until three years from the date of purchase to see if problems develop, and can contact any local Apple Store, Apple Authorized Service Provider or simply call Apple Technical Support if the card develops issues.