PC Not Booting Until a Different Phase is Used?

2by4 asks: "I run at IT Dept for a small firm, our network room houses production & development servers. Some machines are plugged straight into a strip with no UPS. Here is the Mystery Problem: When the power glitches, the strip machines go down, and some of these machine WILL NOT come up again until I switch them to a new outlet. Once this happens, I can put them back on the original outlet and they will work. Unplugging & replugging on same outlet is not enough. I have seen this on at least 5 machines so far, with independent confirmation. We can narrow the 'fix' to plugging into an outlet of a different phase (there are 3 separate 120v phases powering the room). The symptoms vary from no powerup, to frozen at the BIOS (depends on motherboard make), etc, but consistently, switching to a new phase fixes them. I tried the 'unplug-wait-&-replug' cycle, to no avail. Using a new outlet w/ a different phase is the only solution. Any theories? I assume the new phase is causing something to 'reset', but what? I can provide more details, but I am wondering if anyone has seen this before? I am completely and absolutely stumped. Our power is healthy, lightly loaded, evenly distributed and the power strips are new. I know I should have at least a simple UPS, but this mystery is causing me to lose sleep."

Comments

Hmm

[pclminion]

Have you tried shorting the two power pins of the power plug together? Just tap'em simultaneously with a screwdriver. Maybe a capacitor inside the power supply is charged up and somehow it's blocking the flow on a different phase. If so, it's crappy engineering.

Obviously, I mean that you should do this with the plug UNPLUGGED.

Gateway

[gmerideth]

We had a customers Gateway machine that often did that exact same thing. Machine would refuse to boot or crash at the BIOS with invalid memory errors. Swapping the outlet to a plug across the room would cause the machine to boot just fine and stay running for months on end. Even moving the plug back to the original outlet would be fine for a while. The kicker is, it wasn't just the computer. Plugging in his palm would cause the palm to reset while sync'ing and glitch during regular use.

Our Fluke meter showed nothing special on the line and an APC UPS showed no spikes nor higher than normal voltage levels.

To this day we call it the haunted outlet and tend to just keep things away from it.

As an EE student, my professional opinion is:

[Anonymous Coward]

Gnomes?

(Flunking, in case you couldn't tell)

Are you sure your power is all the way recovered?

[argStyopa]

You mention when your power 'glitches'...brownout or blackout or spike?
We are a light industrial building in a heavy industrial park, and I swear the power goes glitchy 2-3 times per year.

We'll get brownout and blackouts, and when the power comes back it SEEMS like it's on, but only 2 of the 3 phases of the A/C actually comes up, meaning (depending on how it's wired at the *circuit box*) some circuits are dead, some are full, and some are semi-brownout (our flourescent ballasts LOVE that half-state.....not).

That third phase sometimes doesn't come back up for hours.

I have no idea if this is of any help, that electrical stuff is arcana to me, I'm just reporting what we've discovered.

What Would Jordi Do?

[Akito]

Did you modify the phase variance?

Check the Neutral To Ground

[getagrip]

We just got a 30 amp circuit installed for a 3kv ups. The UPS once powered up had a "check building wiring" light on the back that came on and stayed on. The cheapy circuit tester indicated that the wiring was fine along with an electrician verifying that all the wiring from the panel to the outlet was correct. One more symptom of this area is that light bulbs blow out much more than normal, although the PCs have not had anything unusual happening.

We had the original electrician who installed the line back out to test. His voltmeter was showing about 20-30V between the neutral and ground. According to code (IANALE), these lines are supposed to be connected at the panel. Apparently without this connection, the two sides coming off the transformer can float in the voltage which may have been responsible for the light bulbs blowing. Once the neutral and ground were connected, the wiring fault light went out on the ups and everthing has since been fine.

SHORT RESPONSE: Have a licensed electrician check out your circuits.

Re:Check the Neutral To Ground

[sakshale]

SHORT RESPONSE: Have a licensed electrician check out your circuits.

Amen!

I actually worked on a system where printer interfaces were burning up because an electrician had reversed neutral and ground in the outlet where the printer was plugged in. There was enough of a difference between neutral and ground to damage the interface of the computer.

Drain the Power Supply safely.

[cravey]

I've run into this type of issue several times. The issue is'nt so much moving the plug, it's that the MB maintains power for up to a couple of minutes after the power is lost. If the Power glitched, the MB may be in a non-useable state. The way I solve the problem is this:
1) Unplug the Power supply.
2) Hold down the power button (on the front) for 10 seconds.
3) plug in the power supply
4) Turn on the computer.

I solve this issue with most of my systems by connectiong them to a UPS. Some crash on their own so often that they're not worth a UPS.

Sounds like it could be a grounding problem

[relifram66]

This sounds like it could be a ground problem. I'd check (if you have the capability) the hot-to-ground and the hot-to-neutral with an oscilliscope on the effected outlet. Barring that you can check it with a multimeter, you may find that the neutral or the ground is inductively coupled to a hot phase.

Some other things to check:

The continuity between the outlet and the electrical box (all three wires).

That your grounding rod is correct for the type of soil in you area.

A different power supply.

Also, like a previous poster noted, try shorting the input to the power supply (when it is unplugged), that may give you a temporary fix.