Upgrade 24” iMac video card - ATI Radeon 256MB to NVIDIA GeForce 512MB - Ask Different
Amazon.com: Valley Of The Sun 2 GB Graphics Video Card GPU Upgrade Replacement for Apple iMac Mid-2011 A1312 27 Inch Core i7 3.4 i5 3.1 Desktop Computer, New AMD Radeon HD 6970M
Amazon.com: Genuine Graphics Card GPU Replacement, for iMac 2008 24 Inch Core 2 Duo 2.8 Desktop PC MB325LL/A A1225, ATI Radeon HD 2600 HD2600 Pro GDDR3 256MB MXM Video Board 109-B97157-00 : Electronics