Ever since Nvidia released its first chipset, PC building newcomers have constantly questioned whether these must be matched to a like-branded graphics card. Traditionally, however, Nvidia chipsets have had no problems supporting ATI graphics cards, and the inverse became true when ATI later introduced its own chipsets.
But why would anyone do this? The answer was easy two years ago, when Nvidia's clear lead in AMD-compatible chipsets was at odds with ATI's clear lead in graphics performance; such were the days of 9700 Pro and FX 5800 graphics. But while today's chipsets seek to "lock in" graphics buyers by offering unique brand-only features such as SLI or Crossfire mode, the majority of buyers will never use these features. And though a larger number of users may wish to add multiple cards to support an increased number of monitors, chipset brand doesn't affect the use of dual-independent cards.
You can check it out over here. After dozens of tests they conclude there's no need to brand match your graphics cards to motherboards chipsets.