This is my first post. I joined after googling my issue for hours. I have a Gateway desktop, DX4820, it's going on a couple years old by now. It came with a Radeon HD4350. It also has onboard VGA. Yesterday I decided to replace the 4350, so I bought a Sapphire HD6790. I uninstalled the drivers for the old card and removed it from the PCIE slot. I plugged in the Sapphire and discovered it has two 6 pin power connectors on it. The box says 'a 500w power supply with two available power cables is recommended'. I assumed 'recommended' meant 'for best performance'. I plugged in my one available power cable from my 300w power supply, and what happened was...nothing. The graphics card fan came on at full tilt, but the card itself was not even recognized. Video was instead routed to the onboard vga (the bios can be set to auto select or to try pcie first) So here's my issue. Does that sound like something that an underpowered PSU would cause? Absolutely no video and no detection at all by the motherboard? Or does it sound like a bad card? or something else all together? Any help would be appreciated. I just don't want to go and spend more money on a psu to find out it still doesn't work.