Question When is power and bandwidth shared among USB ports?

Rodion15

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Sep 11, 2011
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I’d like to know when power and bandwidth is shared among USB ports on a PC.

Let me give an example and please correct me where I may be wrong:

I have a PC with 5 USB ports: three are USB 3.0 and two are USB 2.0.

My understanding is that:

If you plug two USB Hard Drives to two of the USB 3.0 ports:

If they’re plugged to USB 3.0 ports on the same internal Root Hub, they’ll share power and bandwidth.

If they’re plugged to USB 3.0 ports on different internal Root Hubs, they will each get the full speed and power.

If one is plugged to a USB 3.0 port and the other to a USB 2.0 port, they won’t share the power and speed, as USB 3 ports and USB ports always hook to different root hubs, although the USB 2 port will deliver less power and speed.

…if this is true, then I should check device manager to learn which ports are hooked to which Root Hubs.

Any clarification much appreciated
 
I’d like to know when power and bandwidth is shared among USB ports on a PC.

Let me give an example and please correct me where I may be wrong:

I have a PC with 5 USB ports: three are USB 3.0 and two are USB 2.0.

My understanding is that:

If you plug two USB Hard Drives to two of the USB 3.0 ports:

If they’re plugged to USB 3.0 ports on the same internal Root Hub, they’ll share power and bandwidth.

If they’re plugged to USB 3.0 ports on different internal Root Hubs, they will each get the full speed and power.

If one is plugged to a USB 3.0 port and the other to a USB 2.0 port, they won’t share the power and speed, as USB 3 ports and USB ports always hook to different root hubs, although the USB 2 port will deliver less power and speed.

…if this is true, then I should check device manager to learn which ports are hooked to which Root Hubs.

Any clarification much appreciated
Each and every port has appropriate power rating . USB2 has 500mA at 5 Volts it's 2.5Watts.
Usb3 also 5v but 900mA that's up to 4.5W.
External hubs share power and bandwidth with a port they are plugged in,
 

Rodion15

Distinguished
Sep 11, 2011
683
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19,015
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Each and every port has appropriate power rating . USB2 has 500mA at 5 Volts it's 2.5Watts.
Usb3 also 5v but 900mA that's up to 4.5W.
External hubs share power and bandwidth with a port they are plugged in,
I didn't ask that, what I asked is about ports in the motherboard. Thank you all the same.
 

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