8pin to dual 6 pin

My PSU had failed and I took an old one from different computer it is a Thermaltake TR2 RX 650W and I'm trying to use it in my computer. The only problem is that I have a GTX 980 that needs 2 6 pin PCIe connectors but I only have a 6+2 PCIe connector. My question is can I buy another 6+2 (or 6)...