Yes memory can certainly be an issue when gaming. I don't know how much you have in your system, but you can try running it with just one stick, if it's enough ram to power your games, and see if it has the same problems. But usually with a RAM problem, the computer won't boot at all. The 480 nitro only consumes a maximum 360 watts on a strong overclock, so I doubt it's your psu. AMD recommends a 500+ watt psu so you should be fine. If the RAM idea doesn't work, maybe consider RMAing the graphics card. They are all built cheaply, and bad cards are common. I had to RMA an EVGA gtx 780 sc the first day i bought it.