USB modem issues

March 7, 2009 at 10:34:46
Specs: Windows Vista
I am currently using a USB modem (aircard) to connect to the internet via Alltel Wireless.

Anywhere from 30 seconds to 30 minutes, the modem behaves as if I have physically disconnected/reconnected. What's odd, though, is that Device Manager shows no issues or conflicts during this time. It's as if the modem completely freezes.

I was having this problem previously on XP Pro x64 edition, but I just performed clean installs of Vista 64-bit and 32-bit and am having the same issues. I've gone through uninstalling/reinstalling drivers and software to no avail, USB Root Hubs are not turning off devices to save power, mobo and chipset are up to date, and I even purchased a new USB card thinking it had gone bad.

These are brand new cards (I have been through three, thinking the cards had gone bad). Every card does the same thing. My ISP refuses to be of any assistance at this point, and I'd like to be able to use my main PC instead of my laptop on a daily basis.

As I try and work through this moronic USB modem issue, I've come across some similar situations, most of which have ended up being IRQ conflicts between the USB Host Controllers and audio or video cards.

In particular, I'm looking at IRQ 18 on my machine:

18 NEC PCI to USB Open Host Controller
18 NVIDIA GeForce 7800GT
18 VIA USB Enhanced Host Controller

All IRQ's are being used up to 23 at the moment. Unfortunately, my BIOS only allows me access (PCI or Reserved) up to 15. Vista is not allowing me to rearrange IRQ assignments.

1) Is this IRQ possibly the source of my issues with a USB modem that constantly freezes?
2) How can I get the IRQ assignments changed through Vista?

I can post the other IRQ's as well, if necessary.

PC specs are as follows:

Asus A8N-E, non-SLI, BIOS Rev. 1013
AMD Athlon 64 X2 4800+
Onboard audio
BFGTech GeForce 7800GT
two separate generic USB2.0 cards
Vista Ultimate 32-bit (although issue is similar on 64-bit Vista and 64-bit Windows XP Pro)

Thanks in advance.

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March 7, 2009 at 21:48:33
Have you had difficulties with other USB devices on the computer? Is the computer telling you that the modem has been discontected? If not it might be the service. You could try it on another computer...

I used to have an internet card with sprint and I had alot of problems that sound similar to yours. The problem was their crappy service. You might also try installing a USB card in your computer. Hope this helps!

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March 9, 2009 at 23:47:42
I haven't used Vista, but these procedures for XP should be the same or similar:

USB devices may not work properly in certain USB ports, your power supply may have a problem, and you may have an IRQ sharing problem you need to fix.
See response 3 in this:

"Vista is not allowing me to rearrange IRQ assignments."

You often can't do that in 2000 or XP or earlier 95 and up operating systems either if it's a PCI card - you have to move the card or shuffle card positions to possibly shift which IRQ the card uses - sometimes you can do that if it's an older mboard with ISA slots and the card is ISA.

"In particular, I'm looking at IRQ 18 on my machine:

18 NEC PCI to USB Open Host Controller
18 NVIDIA GeForce 7800GT
18 VIA USB Enhanced Host Controller"

That's not a problem if those are all built into the mboard.

If one of the USB controllers in that list is a PCI card, DO NOT install it in the last PCI slot closest to the center of the mboard - that slot is forced to share it's IRQ with the onboard video or the video card in dedicated AGP or PCI-E X16 slot, and that often causes problem with any card except a PCI video card.

All USB 2.0 conrollers have a USB 1.1 component that is automatically detected by Windows, since way back to Win 98 and WIN 95 OSR2 - the drivers for that are built into Windows and are installed automatically.
XP SP1 and up has support for USB 2.0 controllers, but you must install the mboard chipset drivers in order for Windows XP to have the proper info and install the built in drivers for it. In Vista, I don't know if that is necessary, but it does no harm to install the mboard chipset drivers to make sure.

"VIA USB Enhanced Host Controller"
is a USB 2.0 controller drivers have been installed for.

By the way, generally, more devices work better connected to NEC chipset controllers than Via ones. If you have a spare PCI slot, other than the first one mentioned above, if nothing else works, if you installed a NEC chipset USB 2.0 card, plugged the modem into that, it may work as it should.

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