Here is a posting on Dell's Community Forum that explains why there is 4 USB Root Hubs.
tjpstewart Posted the following at 11-21-2003 03:08 PM:
There are only 2 USB ports on the back of the 8600. But, if you look at the Win XP Device Manager you see 4 entries for "Root hubs".
The 3rd entry seems to correspond to the bottom USB port on the back of the 8600. This "Root Hub" says (in its Properties) that it has 2 ports available.
The 4th entry seems to correspond to the top USB port on the back of the 8600. This "Root Hub" says that it has 6 ports available.
What are the 1st and 2nd "Root Hubs" for? Do I have access to them?
What does it mean when the Properties say the Root Hub has 6 ports available (as for the 4th Root Hub)?
Is there any info on this which I can read?
Thanks in advance for any info.
Dell-Karrell Posted this response at 11-24-2003 12:05 PM.
Thank you for using the Dell Community Forum.
The I-8600 has two USB controllers, each controller has 2 USB root hubs.
Each root hub corresponds to an available "USB Port", even though you may not have "external access" to that port.
So, two of the root hubs correspond to your external USB ports.
The other two root hubs correspond to other internal USB ports/devices.
The BlueTooth device these systems use is a USB device, so there is one of those USB ports/Root Hubs.
The forth root hub corresponds to the media base, which also contains USB ports.
Each root hub can support a certain number of USB device/ports.
That is why the third root hub states it supports 2, and the forth root hub support 6.
The forth root hub can support more USB devices/Ports then the third root hub.
Again, even though you can see these specifications, it does not mean you have external access to these devices/Ports. It is simply telling you what each root hub is capable of handling.
There is no easy way to tell what root hub corresponds to what USB device/Port.
You can plug a USB device into a port, then check the power options for each root hub
to see if that device is listed. Then you would know what root hub corresponds to what device/Port.
Windows does not enumerate or list each root hub in order. So, the first
root hub could belong to internal USB devices, while the root hub at the bottom of the device manager listing could belong to an actual USB external port
So it seems that you can not use the powered USB port. Or can you? That still seems to be the question.