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Intel iMac 21.5" ATI Radeon HD 4670 256MB Video Card, Mid 2010 DIY Parts replacement Video Cards
Graphics Video Card GPU Replacement for Apple iMac Mid-2010 A1311 Core i3 3.06 MC508LL/A MC508 21.5 Inch Desktop Computer, ATI Radeon HD 4670 GDDR3 256MB, MXM VGA Board Repair Parts : Amazon.co.uk:
Maximizing the GPU in your MXM-based iMac | Low End Mac