Kronos, look into your PC case, you'll see a (probably white) socket with 4 wires coming out of it plugs into the CD drive and hard drive. Find a one that looks exactly like it, and plug that into the socket on your graphics card.
Drifting now: Thegraphics card makers needn't supply a power lead.
The expected use of power leads from the power supply is: 2 for the mothers, 1 hard drive, 1 floppy and 1 CD/DVD drive.
Of course you never get that few, but the graphics card manufacturer doesn't have to supply one with it.