USB 3.0 Capacity

I just purchased a new Lenovo T440s laptop (running Windows 7).  It comes with 3 USB 3.0 ports.  I currently have two of the ports occupied by USB 3.0 hubs, one with 5 devices, and the other with 7 devices.  When I plugged my iPhone into one of the hubs I got a message that I had exceed my USB host controller capacity.  How is this possible?  What does it mean?  What can I do about it?  I've used the same configuration for years with my previous T420s laptop without any issue.

Thanks,

Phil
philsimmonsAsked:
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McKnifeCommented:
The devices need electrical power, that's what it's about. The electrical output of USB ports is limited, you cannot connect just as many devices on machine A as on B because the hardware is slightly different.
To change that, use USB hubs that have their own power supply.
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philsimmonsAuthor Commented:
Both of my hubs have external power.
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McKnifeCommented:
Interesting. Normal USB ports would let you connect more devices, maybe it's a driver/firmware bug.
Update your computer's BIOS, your USB port driver and try other USB hubs. if nothing helps, talk to the manufacturer of the hub and/or that of the computer.
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philsimmonsAuthor Commented:
Thank you.
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