usb hub whit 20 ports?
i have a usb hub whit 20 ports on an imac 3.06 intel core 2 duo. but i can use just 10 ports. why?
iMac, OS X Mountain Lion (10.8.5), usb hub ports
Best guess, given no information about the USB hub, is that it can't supply enough power to all 20 ports when used with unknown devices that may or may not have varying power requirements.
Crystal ball territory.