Weird, I have 2 USB 3 hubs connected to my Pi, working perfect (8 usb miners running from it, 1 ztex fpga, and 1 bfl fpga)

what distro and what hub if i may ask?

Raspbian - http://www.cumps.be/btc for the image

The Pi itself is also powered from it

How they look: http://users.telenet.be/tr/btc/Miner4.png