AMD RADEON HD 6770M 512MB GRAPHICS CARD + HEATSINK - Apple iMac 21.5" A1311 2011
This AMD Radeon HD 6770M with 512MB of VRAM is compatible with all Mid and Late 2011 releases of the model A1311. This was the most powerful graphics option available for the A1311 model iMac. iMac 21.5" A1311.