I was putting together a computer for my brother, I've put together computers before without hassle but that was a while ago. These days they gotta have extra power going to the video cards or something. The card is a Nvidia 8600GTS 256MB, the power cable look like a black plug with 6 connections in a rectangle shape (i.e. 2 ROWS of 3) which connects to the back of the card and it has 2, 3 connection white plugs coming out of it which will allow the standard 4 connection plugs such as the ones that go into the back of a CD/DVD Drive to be plugged into it. My question is do I need to connect both of these white ones or just one?"When in doubt, try it out"

Try both configurations; first using just one connector. If the video card FAILS to work, you KNOW you're supposed to use both. However, do not use both connectors first; if you use both and you're only supposed to use one, you'll overload the card with too much power, and POSSIBLY damage it.What does the video card manual suggest ? ?It actually didn't come with one. But it doesn't matter, I am currently running it with two under direction from the Nvidia forums and EVERYTHING is fine.If you have only an 8600 GTS, one 4-pin molex connector should suffice, but be aware that the usage of 2 of these is the norm.
Also note that if you do not already have a 6-pin power connector coming out of your PSU, you cannot run this card.