How do I run two video cards at once?

I heard that if I buy two of the same video cards and install them, I can run them together as if they are one, thus doubling there power. Is this true? if it is, how can this be done? Tahnk you so much!

How do I run two video cards at once?
yes you can, nVidia call it SLI technology and ATI call it crossfire, but it not double the performance but just 135-155% performance.


first, you must buy motherboard that support SLI or crossfire features. second, buy VGA card that has SLI or crossfire features. third, enough power supply, large size RAM (min 2G), powerfull processor, big chasing.
Reply:The cards must both be Pci-express and you must have a motherboard with 2 pci-e 16x slots. SLI gives an increase of around 30-60%, but crossfire gives a slightly higher performance increase. You also need the bridge that connects the 2 graphics cards together (usually bundled with an SLI ready motherboard)