1x 6 pin to 8 pin PCI-E

I recently (more like weeks ago) purchased a GTX 760 to upgrade my computer with. Not paying attention, I didn't know the card need an 8 pin PCI-E power connector, my PSU does not have this connector. I purchased a dual molex to 8 pin adapter from Newegg..they shipped it USPS...15 days later I still have yet to receive it. The card did come with a dual 6 pin to single 8 pin adapter. My question is, will this card work if I only connect a single 6 pin to the adapter and connect it to the 760? It is an ASUS GTX 760 Direct CU II OC. My PSU is a 500w.

No, you should have two 6 pins connecting to that adapter. Just wait for your molex adapters to come/ ask newegg when is your delivery. Or a more expensive approach, get a better PSU that will offer 2 6+2 pins PCIE so you don't have problems to future single gpu upgrades.