Okay, this one is stumping me, and I feel like I'm missing something obvious. Here's the situation:

I have a user who found herself unable to browse the web. Simple enough, I get that a lot. I get to the computer and see a red X over the network icon in the system tray. Okay, I go to see what her adapters are reporting. There are none. The network adapters window is empty. I go to device manager, and there isn't even a category for network adapters.

Okay, weird, but again, I've seen plenty of onboard network adapters go bad, so I figured that's all it was. All I had on hand was a USB wireless adapter, so I set her up with that and was on my way. In the meantime I ordered a PCI Express 1x network adapter card just to have on hand.

I get another call from the user saying she has no internet. I get another cancelling that call because it's back. I get a third cancelling the cancellation because it isn't working again and stays that way. I go out and find the exact same situation, now applying to both adapters.

I open up the computer and go to put the PCIe card in. I then try to turn the computer on and don't even get the POST. I try each slot, and nothing at all happens when I try to turn the machine on. If I remove the card, it boots normally, if I put it in, all I get is fan noise and a little hard drive activity.

So I remove the card and boot up. Now I have the adapters back.

I've scanned for viruses, I've checked event logs, and I've done as much research online as I can think of. I was only able to find a single thread that actually matched the symptoms, but the thread had no resolution (as always seems to be the case...).

Does anyone know what's going on here?

Dodgy power supply?

Dodgy motherboard (something on one of the buses including the USB interface). Are there any other devices missing?

Certainly a weird one.

Yeah, dodgy motherboard. Try disabling the onboard network adapter, then putting in the card.

To avoid different issues overlap and create more confusion: are you positive the adapter PCI version is compatible with the MB PCI supported versions? How old is the MB?

In any case, it would seem a MB issue to me as well.

Perhaps, but I don't see any other examples of odd behavior that might indicate that.


Not that I can tell. She doesn't use a ton of devices, though, so that might be masking it.


It is!


But I can't disable the card because according to the computer, it doesn't exist!


Hmm. I've been out of the PC hardware game for a while, but I wasn't aware of this. I would have expected (reasonably, I think) that a PCI Express card will work in a PCI Express slot. The computer isn't very old, just about 15 months (so of course, it's just outside the warranty). I would think it would support a simple network card. If there had been a regular PCI slot available I would have used it (the cards are cheaper), but it only has 3 PCI Express 1x slots.


I might agree with you guys, but for this: so it stopped seeing the USB wireless NIC. Okay, but then why did the keyboard, plugged into the slot next to it, keep working? And the mouse too? I've had a computer with problems on the USB power side, but this seems different.

Very odd.

What happens when you boot off a Live CD?

Because wireless USB adapters draw more power than keyboards and mice? Not saying that this is your problem, but don't discount it.

I'm not sure, but there's no way I'll get her to try it long enough to get an idea if the same thing is happening. The most frustrating part of the issue is that I'll go there, open the machine up to put in the network card, boot the computer back up, and the NIC is back and recognized. Then I'll leave and a day or two later she'll call to say that it's out again.


True, true. I guess I just thought there would be more evidence of bad power to the USB devices...

So does a simple reboot always cause the NIC to come back?

Then it is new enough. It will support PCI Express cards of all versions, i would say.

PCI Express comes so far in versions from 1.0 to 4.0 . This wikipedia entry has a list of them: http://en.wikipedia.org/wiki/PCI_Express
I am not sure if the 4.0 is already in the market. 3.0 is old enough to definitely be in the MB of the PC you're supporting. Every version is backwards compatible.

Not every time as far as I could see

Faulty MB indeed, I think.

Either that, or the PSU. A bad PSU can cause all sorts of strange stuff...

A bit late to this one - does bios setup show the onboard NIC?

-jk