Apple Begins Faulty Graphics Card Replacement
 

Apple began the task of addressing complaints from iMac owners this week by replacing faulty graphics cards on certain models of iMac sold during a specific period of time. Owners have a three year window in which to get a replacement. Those affected by the issue can take their iMac in for evaluation at the Genius Bar of a local Apple Store or an Apple Authorized Service Provider.

http://www.hardocp.com/news/2013/08/...d_replacement/