What hash rate should I expect using a BiFury with USB2.0 rather than USB3.0? I'm considering the BiFury which is generates ~5GH/s on a USB3 port. They say,


  Miner is designed to be used with USB 3.0 port or USB 3.0 hub (must meet min. 0.9A per port to achieve full hashrate)
  USB 2.0 support is also available but hashrate will be lower.


However they don't quote an expected hash rate for USB2.0. Will it be significantly lower?
I found that some USB2 hubs with enough amps (3-4) can take 3 BiFury each easily reaching 5.2-5.6 GH/s. I have 5 running off two 5V 3A hubs daisy chained off of a RaspberryPi with minepeon, works well. You 100% need a couple of fans to keep these cool, I am using arctic breeze, works fine. Errors are at about 4% and temps range from 38 to 50°.

So, the conclusion is… USB2 will work well with BiFury just make sure you have a good amount of amps to supply the thirsty 0.9A they need each! I think they are a good miner for people to get started without spending to much.