What kind of 650 watt power supply. According to Gateway, the stock options are 500 W / 750 W / 1000 W, so I assume you have replaced the stock one? If so, with what brand and model? Unfortunately 650 watts means little. What is really important is the amount of amperage on the +12v rail and whether you have the proper PCIe connectors or spare 4 pin Molex for adapters.