It looks like it could be a bad card, which is not unheard of even from new out of the box. If you can test it in another compuer, or failing that take it back and get them to test it.
What you listed for a power supply leads me to believe that it is some no name thing, that in all likelihood shouldn't be trusted to power a light bulb, never mind a computer.
P.S. based on the rest of your specs, unless budget is a concern you might want to look a lot further up the video card food chain as that HD 3640 is several generations old and was low end even when it was new 4 or 5 years ago. It definitely doesn't do just to the i7 2600 CPU you have.