[TriLUG] why does usb card on PCIe bus need extra power to detect a disk?

[Joseph Mack NA3T via TriLUG]

On Thu, 13 Dec 2018, Brian Henning wrote:

>> I'm wondering why this PCIe card is recognised by the kernel, but needs power 
>> for the external usb disk to be detected.

looking at a bunch of these cards, some of them need power (either via a Molex 
ATA type connector, or through a SATA power connector), some of them proudly say 
they don't need extra power and say they get it off the PCIe bus.

Some of the ones that say they need external power say they need it to power the 
external disk(s). Well I already know that, but I don't know why the external 
disk needs power and I don't know why the power can't come off the PCIe bus.

Joe

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Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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