Your power supply is way too over sized for this set-up. Most of the power supply perform the best when the load is from 50%-80%, so, if u are not planning to do any graphic card update in future, you should consider lower power PSU and save the money at the same time.
You can do some rough calculations here http://extreme.outervision.com/psucalculatorlite.jsp
Your graphic card doesn't have power plug because it is just an entry level kind of card and doesn't consume much power, so, the power from PCI-E lane is enough to power if.
If you are thinking of doing some gaming down the road, better top-up a few hundred bucks and buy a good graphic card.