Yup you're good to go - the 6+2 PCI-e power connector functions as both an 8 pin or if necessary a 6 pin. Just plug in the 6 pin part and you're fine. I have the same thing with my rig. The 8 pin connectors deliver more power than the 6 pin, so this just means your PSU is designed to deliver more than your 7950 will need.
Thank you very much.