Sorry, missed it. That is not enough power to run a 770. Good you didn't install it.
Nvidia recommends, for a GTX 770, a minimum 600Watt power supply for the entire system with at least 42Amps on the +12V rail and depending upon the either 1 6pin and 1 8pin or 2 8pin PCI-E connectors.
The Rosewill Stallion has only one PCI-E connector (6 pin) and is only rated to a total of 31 amps;
It will not power your system and a single GTX 770 video card
In addition the Stallion series by Rosewill is NOT a well made unit. It doesn't have Active Power Factor Correction (obvious from the red switch in the back) and the manufacture is not a top-of-the-line company, Solytech. The Rosewill CAPSTONE series is a very good PSU made by Super Flower, and you might want to consider upgrading to it. I would suggest one of these, or another unit from a reputable company/manufacture: Corsair (not the RM series, to new and has or had bugs), Seasonic, XFX, Antec, EVGA V Series. And I would probably buy too much power, but I wouldn't go under 620Watts, and check the amps on the 12V.