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UHF
All static, all day, Forever
Premium,MVM
join:2002-05-24
Reviews:
·Mediacom
·Callcentric
·Dish Network

Won't power on with ethernet connected

I have client with an older Dell Optiplex GX280 that was never connected to the internet, but now needs to be. This is in a fairly specialized application in a paint store, and it's not so simple to just swap out the PC for a different one since we'd have to reinstall the color matching software and we're not sure how involved that is with licensing, etc.

Anyway, here's the problem. With an ethernet cable plugged in (other end to switch) when you try to power on the power indicator turns amber and the fan spins up to maximum speed but the computer doesn't come on. Unplug the cable, it powers on. Then connect the ethernet cable, and it works fine. Until you shut down again. Installed a known good 3com 905 NIC and that doesn't change anything.

If you unplug the power to the computer and plug it back in, then it will power on with the ethernet connected. Once.

I'm a bit stumped by this. Why the heck would an ethernet cable prevent the system from powering on?

I know the long term fix is going to be to replace this machine, but due to a time constraint (we need this computer tomorrow am) we have to live with it the way it is for now. Hopefully next week we can replace it. I'm more curious about why it does this than anything.

Any ideas?


Veloslave
Geek For God
Premium
join:2003-07-11
Martinez, CA
kudos:1
BIOS version?

JoelC707
Premium
join:2002-07-09
Lanett, AL
kudos:5
reply to UHF
There's a few things to check. You already tried a different NIC so that rules out a failing NIC. Is the cable a structured in-wall cable or just a patch cable to the switch? Is the cable damaged in any way? Is any part of the cable segment home-made or is it all a "factory" cable? Try another port on the switch?

Given it appears to be a power related issue, it seems like something may be shorted, either the cable or the switch port or both. Given you can unplug and replug the power cable and it will boot with the ethernet cable attached, that also seems to lead to some kind of power issue or short relating to the ethernet. Why it only allows you to boot like this once is a mystery, as is why it doesn't seem to exhibit any issues if you plug in the ethernet after it's booted.

bbear2
Premium
join:2003-10-06
94045
kudos:5
reply to UHF
Try a different PCI slot for the NIC. If none available, can you swap it with another PCI card?

How long is the Ethernet cable you plug into it? Since the cable is the apparent cause why not swap out the cable and try a different port on the switch? Have you tested the cable for shorts?

Once the system is up and running (through whatever means) can you connect to the internet with proper speed?

n_w95482
Premium
join:2005-08-03
Ukiah, CA

1 edit
reply to UHF
On the back of the PC, between the VGA and USB ports, should be four diagnostic lights. What pattern is shown when it doesn't boot?

Look around on the motherboard for swollen/puffy/leaking capacitors. I bet there's a few scattered around. Optiplex models of that era are notorious for bad capacitors. This may be of some interest to you.
--
KI6RIT


UHF
All static, all day, Forever
Premium,MVM
join:2002-05-24
Reviews:
·Mediacom
·Callcentric
·Dish Network
reply to UHF
I don't know the BIOS version.

Cable is a 100' factory made cable, we pulled it through a dropped ceiling. It didn't catch on anything up there, so it doesn't seem likely that it got damaged, but it is possible.

Have tried multiple ports on two different switches.

This occurs with the integrated NIC and the 3COM NIC plugged into a PCI slot.

System does connect to the internet once it's up and running. I didn't run any speed tests, the internet connection is pretty slow there in general, but pages didn't seem any slower to load than they are on other machines.

Didn't know about the diagnostic lights. This poor computer lives inside a cabinet

Didn't notice any bulged caps, but I honestly didn't look for them. I probably should have just based on the age of that machine. I've had a LOT of electronics die from bad caps. I scored a really nice 37" LCD TV for free that just needed a few caps changed

Thanks for the replies! I won't be able to be on site today but I did leave him a spare ethernet switch I had, I'll have him plug into that with a short patch cable and see if the problem still occurs.


OldCableGuy2

@communications.net
reply to UHF
Amber power light when pressing the power button on the 2x0 series optiplex means power supply failure/trouble with flea power.

bbear2
Premium
join:2003-10-06
94045
kudos:5
reply to UHF
So could it be that your power draw is near maxing out and by adding the additional power requirements when the cable is plugged in overloads the PSU and shuts down?

When plugging in the cable, it could cause enough of a little current spike to put the PSU over the top. Using a significantly shorter cable (100') could help because of less power it has to use to drive the shorter Ethernet signal. If so, then don't automatically assume it was the cable. Swap the PSU?

JoelC707
Premium
join:2002-07-09
Lanett, AL
kudos:5
That's possible but it would have to basically be right AT capacity already. I don't think the NIC pulls much more power when it's port is active. Also, assuming the onboard NIC was left online when the 3Com NIC was added, shouldn't that cause the same issue if it's that close to overloaded?

It's certainly possible, I've had a similar issue with a borderline overloaded PSU 10+ years ago. I left the side panel off and had to unplug the CD drive during bootup. I could easily plug it back in after it was past POST but it wouldn't boot with it plugged in. I could unplug other things and get it to boot too so it wasn't the CD drive at fault, I just figured a CD drive was better to risk damaging than a hard drive with data on it lol.

If that's really the case, and it can't drive a 100' cable, you could test that by dropping a switch there and using a short patch cable to the switch instead of hooking to the long cable (which ironically he mentioned leaving a spare switch and wanting to test this theory anyway it seems lol).

bbear2
Premium
join:2003-10-06
94045
kudos:5
Excellent points Joel. I wasn't thinking so much as the quiescent power draw, but rather the transient currents resulting from start-ups (cable plug-ins, etc.).

32207098

join:2013-12-19
Anaheim, CA
reply to UHF
May be just an Ethernet driver problem. Or, is the earthing proper? And what about the BIOS?


Tursiops_G
Technoid
Premium,MVM
join:2002-02-06
Norwalk, CT
kudos:1
reply to UHF
Just a thought...

Check the Boot order in the PC's BIOS setup, and make sure that booting from LAN (PXE) is Disabled...

-Tursiops_G.
--
If You're Unsure, "RTFM"... If You're SURE, "RTFM" Anyway.


Anonymous_
Anonymous
Premium
join:2004-06-21
127.0.0.1
kudos:2
Reviews:
·Time Warner Cable

2 edits
reply to JoelC707
Click for full size
said by JoelC707:

That's possible but it would have to basically be right AT capacity already. I don't think the NIC pulls much more power when it's port is active. Also, assuming the onboard NIC was left online when the 3Com NIC was added, shouldn't that cause the same issue if it's that close to overloaded?

It's certainly possible, I've had a similar issue with a borderline overloaded PSU 10+ years ago. I left the side panel off and had to unplug the CD drive during bootup. I could easily plug it back in after it was past POST but it wouldn't boot with it plugged in. I could unplug other things and get it to boot too so it wasn't the CD drive at fault, I just figured a CD drive was better to risk damaging than a hard drive with data on it lol.

If that's really the case, and it can't drive a 100' cable, you could test that by dropping a switch there and using a short patch cable to the switch instead of hooking to the long cable (which ironically he mentioned leaving a spare switch and wanting to test this theory anyway it seems lol).

he should check the caps on the main board for signs of bulging

they might be no good

here is a photo of my GX280 mini tower with good caps


LuLuLemon365

@optonline.net
reply to UHF
Until you can trace down the power draw problem, get a USB to ETHERNET NIC for your system. Here's one for about $20+ and supports OSes from W2K to 7 to include MAC OSX. Google search for vendors (GWC AE2302 USB 2.0 to RJ45 Gigabit LAN Adapter Cable).

bbear2
Premium
join:2003-10-06
94045
kudos:5
reply to UHF
Any update?