Not sure about the cap, but that could be protected. I do like the multiple power and ground wires. Most powered risers I've seen only have one +12v wire, no ground.
Where did you find them? Price?
Thx
Most of them don't have extra grounds because you don't actually need them, especially on x16 slots
http://en.wikipedia.org/wiki/PCI_Express#PinoutEven an x1 slot has 9 ground pins.
All the grounds on the card are tied together as well, so you've got 6 or 8 or however many ground wires on your PCIe power connectors.
The main reason for powered risers is that most motherboards weren't intended to have six graphics cards on them, and they only have two +12V wires on the ATX connector to supply all the PCIe slots (but 8 grounds).
http://en.wikipedia.org/wiki/ATX#Power_supplyIn my rigs I use three unmodified risers and three where I have the +12V lines completely disconnected from the motherboard and running to a separate power supply.
The capacitors are pretty much irrelevant, I would think...graphics cards will already have them. Someone probably just figured they could mark the riser up $3-5 by adding a $0.10 part to it.