I didn't think I needed to power the 2-port version either, but I had to. The MP recognized the card upon bootup, but disabled the card with a message about how a USB device was using too much power so it shut the card down.
I too have all bays full, both HDD and optical. Nevertheless, I used a y-cable in the optical bay to get power. You can indeed run power there through the tightly integrated case.
See this post. I can provide pictures if it helps.
This is the particular card I used.
Everything is powered now and works perfectly
with native drivers, which was the whole point. I didn't really want to hook up extra power, but now that I have, I can confidently use a bus-powered device if need be.
Here are the cables I used:
1)
This one splits the SATA combo plug into separate data and power. It sits in the optical bay.
2)
This one is the Y-cable for power. It sits in the optical bay.
3) The SATA-to-Molex adapter comes with the card and sits in the optical bay.
4) Finally,
this cable runs from inside the optical bay to the card.
You have to temporarily remove one Molex connector from that last cable to thread it into the optical bay. I used the same route as the default SATA cabling.
In retrospect now that I've run power, I might as well have gotten the 4-port. The price difference is miniscule.
I don't mind forwarding one. PM me if you like.