Amazon.com: Tarjeta gráfica original GPU de repuesto para Apple iMac A1311 Mid-2011 Core i5 2.7 MC812LL/A MC812 computadora de escritorio de 21,5 pulgadas, AMD Radeon HD 6770M GDDR5 512MB piezas de reparación :
2011 iMac Graphics Card Upgrade | How to | Mac Expert Guide
Amazon.com: Tarjeta gráfica original GPU de repuesto para Apple iMac A1311 Mid-2011 Core i5 2.7 MC812LL/A MC812 computadora de escritorio de 21,5 pulgadas, AMD Radeon HD 6770M GDDR5 512MB piezas de reparación :
Amazon.com: New HD 6970M 2GB Graphics Card Replacement for iMac Mid-2011 27" All-in-One Desktop PC Core i7 3.4 MD063LL/A MD063, AMD Radeon HD6970M HD6970 GPU Upgrade MXM Video Board Repair Parts :
The New 2011 iMacs: Specs and Details
upgrade - Ordering a 21.5" iMac with a different graphics card - Ask Different