I recently built a computer with Gigabyte UD3, Intel i7, OCZ ModXstream Pro 700W, and Sapphire HD4870 1GB (if you need other specs, let me know). When everything except the Sapphire is connected, everything boots fine (but I cannot see anything, obviously). When I connect the graphics card, it boots for about 10 seconds, then turns off. A few seconds later, it boots back up and then turns off at the exact same point (over and over again). The point it turns off is within a second of showing the first screen, which tells you which keys to hit for BIOS. I tried a new power supply and a new card (same models, thought they might be defective). Any idea what could be causing this?