Be careful when fixing other peoples computers!

[peterb]

First off, the unit of current is mA - Mah would be williamp/hours is a measure of current drain per hour used to callify battery capacity and discharge rates!

The problem with the USB spec is that it has evolved (wonderful thing about standards is that there are so many to choose from!) over time so while the original USB spec defined a maximum current of 500mA (partly because of the contact design) later improvements/changes in the connector technology allow for higher currents. Some of these are proprietary and are outside the USB spec - examples are things like bar code readers or specialist printers used in the retail industry.

The spec also provides for power negotiation, but only true USB compliant devices will be able to do that - a passive USB device (a USB fan, or coffee mug heater for example) won't do that and may attempt to draw more power than the computer it is connected to can supply.

As to a USB device being damaged by a mobo - I wpould have thought that unlikely unless the connector had been mis-wired, and given the modular design of the headers, I would have thought that unlikely too, but without looking at the specific instance, it is difficult to comment with any certainty. However, connecting a later USB device peripheral to an earlier spec source is a more likely scenario.

But USB flash drives tend to be pretty low power consumption devices, and so I would have thought it unlikely that a properly functioning one would cause damage to a PC.

[shaithis]

Older cases had singular wires instead of the "connection block with one hole covered" connector you get now.......might be worth checking whether its the old style or not before inserting any USB devices in future.......I've seen them randomly wired way too many times.

[watercooled]

Kind of unrelated but I know my 2.5" external HDD makes a sort of buzzing noise and wont work if I use the thinner cable provided with a 3.5" drive. I'd assume that's because enough current isn't being supplied because the 2.5" drive is USB powered but I though all cables were supposed to be to spec? The one that comes with the 2.5" drive comes with a second A connector for extra power if one port won't supply enough power.

[TheAnimus]

First off, the unit of current is mA - Mah would be williamp/hours is a measure of current drain per hour used to callify battery capacity and discharge rates!

i blame midnight posting.

But USB flash drives tend to be pretty low power consumption devices, and so I would have thought it unlikely that a properly functioning one would cause damage to a PC.

Indeed, but if by putting it into an incorectly wired USB port (and there are plenty of cases nocking about which have each line as its own header!) then its possible something could have broken down.

[laywill]

I admit that my case came with the USB front panel connected by a number of individually headded wires. Thankfully the nice people at Asus had the foresight to provide me with a selection of Q-Connect headers for USB telling me nicely where to plug each strand. So far I havent blown anything up...

[Vimeous]

i blame midnight posting.

That'll teach me not to copy ya!

I admit that my case came with the USB front panel connected by a number of individually headded wires. Thankfully the nice people at Asus had the foresight to provide me with a selection of Q-Connect headers for USB telling me nicely where to plug each strand. So far I havent blown anything up...

That's why the q-connector is wonderful

[Behemoth]

You should really get a voltmeter Behemoth - using your tongue is a bit old fashioned.

Oh I know, I use them now, trouble is my tongue has gone numb and I can't taste anything nowadays

[peterb]

i blame midnight posting.

Indeed, but if by putting it into an incorectly wired USB port (and there are plenty of cases nocking about which have each line as its own header!) then its possible something could have broken down.

Well I just noticed a typo in my own post!!

Yes - and of course the faulty drive could in turn then cause damage. However, in this case with an older computer, it wiould be surprising if a USB port wiring fault hadn't been discovered before. (Or maybe it has, and left a trail of trashed USB devices in its wake!)

[dangel]

This happened to me as well once - moral of the story really is to back up usb drives just like any other (and choose one with a lifetime warranty) hehe

[goku127]

I only use my cheap 4gb usb drive to fix computers. Definatley won't be using any expensive equipment. So far nothing bad has happened to it.