OK...the newer cards that support DirectX 10 (G80's and R600's) will need a PSU that will have to use 1K -1.2k power supplies or an extra power supply that would fit in a optical drive....well that presents a problem for some people including me. I have a door OVER my optical drives so the extra power supply
wont be able to get rid of the hot air and may also damage other components too.

My source: