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I have an external, self-powered HDD, and when I plug it into the front USB port of the computer, it doesn't mount - instead, I see:

new high speed USB device using ehci_hcd and address 15
configuration #1 chosen from 1 choice
USB disconnect, address 15

It works fine when it's plugged into the USB ports at the back of the machine (which are right on the MB). Other devices - usb keys, my cameras, etc - work fine in the front ports.

Does anyone have an explanation for this? Could it be power related?

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Do you see the device in the lsusb output after this happens? – nagul Aug 15 '09 at 18:23
up vote 0 down vote accepted

It's likely power related. Many computer manufacturers does not supply enough power to the front ports of the computer. This is the reason that you should never use the front ports for power hungry devices.

If you're wondering if this is the case a simple call to your computer manufacturers support should verify my claims.

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it could be a loose connection with the port on your computer. I'd see if wiggling the connector makes the computer detect the drive again.

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The port works fine with other devices, just not the HDD, so I doubt it's a loose connection. – chris Aug 15 '09 at 19:13
OK, I was just thinking, if the full weight of the USB cord is supported only by the port, it might break the connection, while lighter devices wouldn't put the same force on the port. But like you said, it's unlikely. – Babu Aug 15 '09 at 19:36

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