iMac Intel 21.5" EMC 2428 (Mid 2011) Graphics Cards
iMac Intel 21.5" EMC 2428 Radeon HD 6750M Graphics Card
Replace a Radeon HD 6750M graphics card in a Model A1311 Mid 2011 21.5" iMac.
iMac Intel 21.5" EMC 2428 Radeon HD 6750 Graphics Card
Replace a broken or malfunctioning Graphics Card in your iMac 21.5" (Mid 2011) desktop.
In May 2011, Apple upgraded the 21.5" iMac. Externally, the machine features edge-to-edge glass and an aluminum rear bezel. Internally, an LED display, 4 RAM slots (to upgrade to a maximum of 16 GB RAM), more powerful video processing, and featuring quad Core i5 and i7 processors.