Old thread, I know. I assume you're talking about the little round Gridseed 5 chip miners that are USB powered. The problem is that the combination of several of them draws more power than the USB hub provides. You can get away with 1 or maybe 2, after that you have trouble. It's a common problem with plugminers like Gekko's. If you have some soldering and electronics skills you can beef up the 5 volt supply to the pins of each connector that need it. Or these hubs have a good reputation of working well, since they claim to be able to deliver 70 watts.
https://www.amazon.com/Superbpag-Portable-Charger-Transfer-Samsung/dp/B013OK10YMIt is a USB 3 hub but is known to work with a Raspberry Pi anyway. Take a close look at the fine print on the wall wart or brick that powers the hub, it may not be supplying much over an amp total. As you turn the clock rate up the ASICs draw more power, often over an amp each. The USB 3 specs call for more current at each port, but Raspberry Pis don't like most USB 3 hubs.
My Gridseed is a G-Blade with 80 chips, it draws about 100 watts from a "real" power supply. The USB connections are only for signal, not power, and it works fine.