Thanks for the explanation Paul. I appreciate it!
jdc1
Paul, this is really funny (wierd). I cold powered off and on about 5
times. One time I got 2 beeps and card seen. Next cold boot, 1 beep and
card not seen. Next boot 1 beep and card seen. (HP printer is seen
nicely regardless). It seems as if the power from my Enermax 350w psu
is being routed in a fickle manner thru the boot up process.
I have only hdd, cd-rw, cd-rom and vid and sound card and hp printer.
Is your way a sure fire way without having to ponder why it does that?
I hope I'm not going on too much about this.
jdc1
My theory has been tested to work with things like a USB keyboard. At
least one person managed to get their USB keyboard reliably detected,
if the keyboard was powered by +5VSB. Basically, the idea is, that
power is applied to the device all the time, as +5VSB is running
as long as the switch on the back of the computer is in the "on"
position. This means that your external USB device is powered up
and is ready for the USB packets sent to it at POST and boot.
If instead, a device is powered from +5V, then the motherboard
and the USB device get their power at roughly the same time, when
you press the switch on the front of the case. If the external USB
device has a long hardware initialization time, the USB device may
be "deaf" to the USB packets sent to it.
In terms of other known bugs in USB, Nvidia released a technical note
explaining why the Nforce2 chipset doesn't work with certain USB
chips. They say that some USB devices are non-compliant with the
USB spec, and the devices have too much "clock jitter". What this
means is the data bits on the cable are wiggling out of their
nominal position in time - this makes it more difficult for the
circuit that finds the center of each data bit, to sample it, and
to get the right value. More of the USB packets can get rejected
as having errors, or the interface might simply conclude "I don't
see a device". The Nvidia tech note identifies certain chips and
you can read it here. The workaround is to use a USB2 hub, as
apparently a 2.0 hub "reclocks" the data (and also implies that the
hub is more resilient in the face of jittered data). I'm
not suggesting that this is the problem with the P4P800, but only
note this to say that sometimes the USB devices themselves are
to blame for the problem:
http://www.epox.de/_boarddetail/8rda+/nForce2_MCP-T_MCP_USB1.1_AppNote.pdf
For the longest time, people have complained about certain ports
on their motherboards not working, and I have to wonder if this
kind of thing was the root cause.
With respect to using USB on the front of the case, some people in
this group are reporting that the cabling that comes with some cases
is not USB 2.0 compliant, so they can only get the USB connector
on the front of the case to work at USB 1.1 rates. So, if you have
further trouble when using the front ports, just move to the USB ports
on the back of the machine. Due to the 480Mb/sec data rate, a USB 2.0
cable has to have very good transmission qualities to work properly.
A handful of loose wires isn't going to cut it. (Look at an Asus adapter
plate, as some of them look better constructed.)
Finally, the BIOS can contribute to the problem. Perhaps a later BIOS
has improved detection, simply by waiting a bit longer before probing
the USB ports, or going through the reset procedure a few more times.
HTH,
Paul
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