Upgrade 24” iMac video card - ATI Radeon 256MB to NVIDIA GeForce 512MB - Ask Different
Original Graphics Card for Apple iMac Early 2008 24-Inch A1225 Desktop Computer Core 2 Duo 2.8 MB325LL/A, ATI Radeon HD 2600 Pro GDDR3 256MB, GPU Upgrade Video Cards Replacement Spare Parts
iMac Graphics Crash | MacRumors Forums
hardware - 27" iMac late 2009 - Monitor and graphics card broken - Ask Different