You can use splitter or search for another PSU with more PCI-E

https://www.amazon.de/Corsair-RM850x-PC-Netzteil-Voll-Modulares-Kabelmanagement/dp/B015Q7F4WA/ref=sr_1_3?ie=UTF8&qid=1524992393&sr=8-3&keywords=psu+1000w&dpID=51TNs3B0ScL&preST=_SX300_QL70_&dpSrc=srch