Apple initiated a repair program for 2011 iMacs with similar GPUs.



From ArsTechnica:

The 2011 MacBook Pros were sold between February of 2011 and June of 2012, with a slight spec bump in October of 2011. All 15- and 17-inch models included Sandy Bridge processors from Intel, and the laptops will switch between the CPU-integrated HD 3000 GPU and the dedicated AMD GPUs depending on your workload. That the problems reportedly crop up more often under graphical load suggests the issue is with the dedicated GPU, not the integrated one. The 13-inch laptops all used integrated graphics and don't appear to be affected.

  Report: Some 2011 MacBook Pros with AMD GPUs experiencing hardware failures