I'm assuming that the manual came with the mobo. Read the book.
I pulled this from the manual for you.
Exclusive Graphics power Connector: PWR3
This connector is an auxiliary power for graphics
card.Exclusive power for graphics card is for
beter graphics performance and future upgrade
8-pin ATX_12 V Power Connector: PWR2
The 8-pin ATX 12V power supply connects to
PWR2 and provides power to the CPU.
Edit: the Antec only has a 4pin connector. it needs to be connected to pins 1,2,5,6. Check the manual for a drawing.