Ironsounds :
Hello... a Video card sometimes needs additional power from your Power supply... Low power ones will use the PCIe MB connection/slot for it... typically <75 watts models.
Yep, it looks like that PowerColor X460 has a 6-pin PEG connector on the side. So you would need to use the PSU 6-pin connector for it.
If not, than maybe you don't have the Red Dragon model or i'm looking at the wrong one.