[kwlug-disc] intermittent NIC?

unsolicited unsolicited at swiz.ca
Thu Nov 19 13:17:14 EST 2009

Richard Weait wrote, On 11/19/2009 6:22 AM:
> Hunh?
> I have what appears to be an intermittent NIC on a p4 motherboard.
> The board was acquired as surplus some time ago for a project that
> never started so this is the first time I've looked at it.
> Link light appears steady for a while, then out for a while; the
> duration does not appear to be a pattern, or blinking.  I never see
> the super-happy-blinking-lights that I expect from a healthy, active
> connection.  Ping tests on my local network give 40% to 75% packet
> loss.  Using another box on the same ethernet cable / switch port
> gives the expected perfect connectivity.  I see no bent pins in the
> ethernet socket.
> I'm tempted to use a plug-in NIC and forget the on-board NIC.  Am I
> missing something?

Not so common any more, but at one time not uncommon, especially as 
technologies changed towards more switches (from hubs) and towards 
gigabit (from 10 Mbps).

What is the NIC max speed? (10? 100?)

What is the speed of the device being connected to, and what is it? 
(Switch? Hub?) Full-duplex, half-? Manufacturer?

Can you try temporarily connecting it to another hub, preferably the 
latest switch you can find? If it gets stable, you're running into an 
auto-negotiation problem. I suppose even a crossover cable to another 
NIC (of reasonably recent make, say, 5 years) would do, for testing 

You could also try nailing it down to 10Mbps / half-duplex for a short 
time. This should let you know whether (a) bad nic, and/or (b) 
auto-negotiation issue. i.e. If it gets happy, it should stay happy at 
any nailed down setting within the capabilities of whatever you're 
connecting to. With a successful test you could nail it to 100 Mbps / 
full-duplex and probably be OK. [Note gb, by definition, is 
full-duplex. Trying to nail it to half-duplex GB will probably not 
make you happy.]

If you add another nic and disable the on-board one - have an eye. 
I've had issues in that situation where the nic name floats and/or 
won't come up (it choking on the disabled nic and not going on to the 
next one).

In another reply, it says to watch for setting changes when you move 
it to another connection. Huh? A nailed local nic's settings don't 
stay nailed?

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