Apple has been angry with Nvidia for some time now because of the prolonged GPU failures in Mac Computers and iMacs. Thus, Apple has finally decided to shift to ATI Radeon 4000 based graphics chips for their upcoming Mac Pro and iMac computers. The ATI series will replace Nvidia Geforce 9400 based graphics chips.
Apple is having issues with Nvidia based onboard graphics chips due to overheating while using multimedia content or gaming. Thus, the failure rate of Apple products has increased significantly, mostly due to burnt GPUs. This has ignited the company to find other partners to replace the graphics chip. AMD has announced that the upcoming Macbook Pro and iMacs will be equipped with Radeon 4000 series discrete graphics cards. The Radeon 4000 series supports DirectX 10.1 along with OpenCL 1.0 which is supported in the new Snow Leopard Operating System. The graphics chips also supports hardware decoding of HD media. The new graphics cards would be ATI Radeon HD 4870 and 4850 to be used in Mac Pro and iMac respectively.
Nvidia will take a big plunge as a major partner is moving to its competitors. However, Nvidia maintains that the heat issues will be corrected in the next generation graphics cards, and Apple partnership will again start.