I had a problem like that once. It was caused by a bad conection on the power conector on the video card. A friend solder it up for me. Works great now. I run 5 hard drives(2=ide, 3 sata), 2 dvd burners, ATI X1600pro, Water cooler with a 450 watt single rail PS,
The PS your looking at should be fine.
1= I had swaped this card out several time before it had an error message so I must have broke it
2= My friend does secruit board repair, don't try at home.