[Tfug] Failed drive == power problem?

[Zack Williams]

> After the drive had been mounted for a while, however, it began to
> crash my notebook.  It would give me an "Over-current change on port
> 1" error and the notebook would lose power and various indicator
> lights (on the notebook) would start flashing.  The problem seems to
> be with the failing hard drive.  Once I replaced the failing drive in
> the enclosure with a good one, the problem went away.

USB is limited to 5V at 500mA (2.5W), and many drives will use more
than that especially when they're spinning up.   That would most
likely be the cause of your problems.    This is why a lot of USB
external drives ship with an additional USB to power jack so the drive
can use two ports.

BTW, Firewire doesn't have this issue, as it allows up to 30V and 45W
via it's 6 and 9 pin connectors.  However, this can cause other
problems - often cheap cases are made with parts not rated for 30V and
you end up with blown capacitors in the case if they weren't designed
for systems that provide higher voltages.

- Zack