An AntMiner U2 requires 2.95W at 2Gh/s, per the Bitmain website. That means that you must account for .6A or so for each miner, and leave a little extra to keep the hub from burning out prematurely. Six miners are drawing 3.6A, not to mention whatever the fan is using, clearly putting you above max. I saw your ebay post and assume you're not in the U.S., but for what it's worth I am running five of these AntMiners on a Rosewill 10 port hub as well, but the 5V 4A version. http://bitcoinrigs.org/wp-content/uploads/2013/10/rosewell-10-port-usb-port-2.jpg Got it on Amazon. I also don't suggest you buy another psu and try running your hub with it: if the two are not rated for each other, you're probably going to short out/probably destroy your equipment/probably get shocked/probably start a fire. Good luck man