I would recommend powered USB hubs.
Using very successfully .......... I love this device.
MacIntosh MacPro Laptop with USB3.0 port as link to the D3100
I am using OS X 10.10.5
Two HDMI displays
USB 2.0 hub ( for isolation and to reduce connector wear )
USB drawing pad
Powered external speakers
I used HDMI to DVI adapter since my monitors did not accept HDMI cables.
The adapters were $3 each from eBay.
For the Mac I had to download a driver.
If this link quits working... contact me at cinternational.com and I will try to help.
I have no connection with Dell.
777D3100 #DellD3100 777DellD3100 99guspuppet