Thanks anort, that makes me feel better. My concern comes from the fact that this isn't a stock 560 - it's the MSI Hawk overclocked to 950 MHz, so that uses a good deal more power. Add in an overclock on the CPU and that'll push up the wattage even more. In fact, the card just came in, and the back of the box says you need a 600w PSU. I'll still give it a shot with the 550 and hopefully I'll be fine, but at least I feel comfortable that I can swap it out with the ModXStream if I need to. Thanks again!