Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
Thanks but I don't think thats my problem.
The USB mouse only draws 20ma. and a self powerd hub i have hooked up to a
different USB port stops working. In fact all the USB ports stop working with
any device that requires power.
Andy
>> I have this board running Win XP SP1 with 1gig of DDR memory. Every now and
>> then at no particular time frame my USB ports stop working. Any device that
>> requires power stops. My scanner and printer continue to work. The only way
>to
>> get the powered USB devices to work is to reboot the machine.
>> Any ideas on how to fix this?
>> TIA
>> Andy
>
>The USB ports are protected by polyfuses. These are fuses that open
>circuit when they get hot, and close again when they cool off.
>
>The fuses are there to protect against a short circuit on the USB
>+5V from damaging the motherboard. Generally, a USB port is allowed
>500mA of current, and if it draws more than that, the port will
>be powered off.
>
>Check that you aren't using a non-compliant device. An example
>is the Alcatel "frog" ADSL modem, which draws slightly more
>than 500mA.
>
>If you must use the device in question, a possible work around
>is to use a powered USB 2.0 hub to run the device. Sometimes
>they are a little more forgiving than a motherboard.
>
>You can see samples of the polyfuses, just above the USB56 and
>USB78 headers. It is possible the power is also switched
>by MOSFETs somewhere as well (not sure).
>
>Another reason for USB ports to "wink out", is if there is
>some kind of power management issue. I think there is an option
>somewhere in the Device Manager, to allow Windows to power down
>stuff that is not active, and that is another possible source
>of your problem. Since your scanner and printer are working, it
>isn't likely to be power management.
>
>For your amusement, I found a link to a doc on usbman.org . Usbman
>has some info on USB and sometimes has fixes for USB problems. This
>doc is from Intel and describes some of the stuff I mentioned above.
>
>http://www.usb.org/developers/whitepapers/power_delivery_motherboards.pdf
>
>HTH,
> Paul
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