Installing graphic card

can anyone help me out? im really stuck with this














i watched a lot of videos on how to change a graphic card, but none of them had this extra wire....im not sure do i need it or not...and if i do how am i suppose to connect it with the wire the graphic card gave me when the ends arent the same?

Thats a power cable to your power supply. The white end goes into your Graphics card, The black into your power supply.