Well, shoot, I can't find the 6600le amerpage requirement anywhere.... The only thing I can think of is that on the 12v rail of your power supply, I doubt 15 amps is enough... But your power supply has a 12v v2.0 with 17 amps, which should be enough, but I don't know much about 12v v2.0... Maybe undertaker can educate us about it .

Another possibility is a bad CPU... I know that a bad CPU will prevent you from seeing anything or hearing any beep codes... I'm not saying go out and buy another CPU , I'm just saying that's a possibility...