So I finally got around to buying a second card for my first SLI setup. I've got dual GTX 760's 4GB editions and when I tried to install them I noticed that I was short 1 6pin power connector for the second card. Is it possible to only plug in the second card with only the 8 pin?
No, it wouldn't work. Looking at the product page for your PSU, it says that it comes with 4 6+2 pin connectors. If you're missing one, you should see about procuring a replacement through Rosewill, often times you can get replacement parts directly from the manufacturer.