When talking to a developer about RealSense and USB power issues, it reminded me of a method I used successfully back in the fall of 2014 when I had a RealSense camera that was not working correctly. If you are technically minded and able to install and uninstall expansion boards from a PC case, you can purchase internal USB 3.0 expansion boards for the inside casing of your PC relatively cheaply.
These plug into a vacant PCI Express format slot on the desktop PC's motherboard and provide an additional set of USB 3.0 ports that are accessible through an opened-up expansion slot on the back of the machine.
Many of these cards also have a set of 4 "molex" pins on the expansion board that you can connect to one of the spare small-plug 5 volt cables extending from the computer's internal power supply unit. This extra 5v supply to the card can help to prevent the camera from dropping out due to insufficient power when the camera laser is performing higher-drain functions such as depth sensing. Not every card comes with these pins as standard, so you should check a particular card carefully before purchasing.
An easy way to research cards that have the power-boosting pins is to google for 'usb 3.0 pci expansion 5v pins'