USB 3.0 cards, do you have to use the molex?

[matt100]

Basically just that, I've got a USB 3.0 device but I'm changing mobo to one without USB 3.0 so I fancy getting a PCI-E card, can it take the power from the slot or do I HAVE to use the Molex?

 

[weird_dave]

I'd say yes. It may not work reliably (or at all) without it.
This seems to suggest 10W max power draw at startup:
http://www.pcisig.com/developers/ma...c_id=6d37ec2f8543fc1f9d8ace6264d08b469f57e5f1
So yes, use the molex

edit:
page 20

 

[matt100]

balls, don't want messy cables.