Well, your card should have some with a molex adapter for it, probably with two connectors merging into one. Make sure both of those connectors have something plugged into them (preferably plugs from different strands, each with little else on them, ie dont go HDD+HDD+Vid card on a single string) and that the single connector that the two ones merge into is plugged securely into your card. As for the voltage, I have no idea.