That is a very old power supply. According to Tom's, it was recommended as one of the best values in 2008, but the community feedback was that the watt rating was way too high.
The user feedback was that it had trouble at over 80% load, so if you treated it as more than a 700 watt PSU it could become unreliable. Power wise, it should be able to handle it. But if your power supply is from before 2010, I would get a new one before connecting a $500 video card to it.
Power supplies do age, you know.
Check out the power supply tier list at:
http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html
A good power supply that should be more than enough for your usage would be something like this SeaSonic M12II ($75)...