Solved Where to obtain power for USB 3.0. PCIE card?

[Comp Cmndo]

USB 3.0 allows current draw of 500ma - 900ma, whereas USB 2.0 is limited to 500ma.
PCI-e connector has no +5V, so the extra 400ma has to come from the PSU. If your USB device requires no more than 500ma, the molex power is not required, If you are using a USB hard drive, it will be needed.

??? worked alright on mine without xtra power

Depends on the power requirements of the device being used. Most notebook type USB hard drives are very efficient. Mine is marked USB 2.0/3.0.

The extra power from the molex would be also needed for charging USB devices.