Remember the 2011 iMac's HDD replacement program? It seems like the machine thought it was time for an encore. Apple recently announced that 27-inch iMacs sold between May 2011 and October 2012 may be eligible for a free repair, citing faulty AMD Radeon HD 6970M GPUs (you can find the official statement after the break). The issue specifically affects machines with 3.1GHz Core-i5 and 3.4GHz Core-i7 processors, and can cause visual distortions, white or blue vertical lines or a solid black display. According to 9to5Mac, Apple is also issuing refunds to customers who paid to have the GPU fixed before the program was announced. Fair enough if you're on a budget, but we won't blame you if you use the issue as an excuse to upgrade.