Extra power is questionable. Contact spring "works its way through the plug".

Even before buying the extra power connector opportunity has fallen into my eye. Immediately after delivery so I have the board examined more thoroughly. From the power supply from the 5V via one diode per port are guided parallel to the already coming from the motherboard power supply to the USB ports. The conductor tracks for this power supply are quite lush dimensioned. According to the data withstand the diode, which is the only in the current path, up to 3A. This does not mean that it works with 3A as a backup, but it is likely to briefly tolerate significantly more. When in doubt, therefore, the USB device is the weakest link in case of failure.

The good news about this: If you simply omit the power supply, then the USB ports are powered via the to be connected to the mainboard USB3 cable. Here then also accesses the intended Mainboard current limitation in case of failure. My advice would be to dispense with the extra power connector prefer.

But what you can not easily fix, is the fact that the mass spring to contact with the metal body of the USB connector, at least on my front panel is very tight and sharp. You could tell when you plug the clearly noticeable scratching that here material is removed. After only a few plug processes can see the result on the USB plug. At the point where the contact springs touch the USB connector, be marked "furrows" dug into the material.