it depends on what psu you are using, good PSu usualy has no problem with it.
I disagree, the power supply has no issue on wether or not any cable can carry that power ( in watts ).
As Example, there are PCIx risers that carry the 8 DATA lines TO/From graphic cards and the wattage is minimal over those wires. They DO rely that the ground for the Graphic cards are on the power line and that the graphic card's case connector is also connected to the case's ground to allow the difference of voltage ( the 1 or 0 being sent/recieved ) to be accurate and not suddenly 120V higher than what the system can handle ( over time a DC signal of 1V can appear as a really high difference of voltage when it does not share ground with the receiving system ).
So, I personaly, avoid thoes USB 3.0 cables for actual power, will use them with PCI riser setups after making sure the ground on both the card and the motherboard is shared. Most of the SATA to GPU adapters do not have the grade of wires to carry enough current for my video cards as the actual wire is too small. The actuall wire diameter will determine what current it can carry before it starts acting like either a resistor ( and heat up ) or fuse ( and have a break in the connection IN the plastic housing ). I tend to check to see if it is ' smaller ' ( actually bigger diameter for lower Gage of wire ) than 28 and how many will be power and how many will be ground.