Flickering Monitors?

Anonymous Coward writes "Our SB Office runs a small 2 Server network with 4 workstations in the LAN, each connected to a dedicated APC Surge protector. The building has a backup power generator thus we didn't see the need for a UPS. For some odd reason all our monitors flicker a lot. We've tried everything from changing resolutions/refresh rates/video cards/monitors and spacing the monitors farther apart from each other - all to no avail. Could this be a building power supply problem? Some have suggested there may be some magnetic interference but visually inspecting the surroundings doesn't leave us with a culprit for the cause. Could this be fixed by the simple addition of a good UPS? Any help, tip or information would be gladly appreciated. Thank you."

Comments

Fans?

[Stigmata669]

I had this problem when I placed a table fan next to my monitor on my desk in the middle of summer. The spinning magnets cause a very annoying flicker, and maybe hopefully not do some damage. Try moving the monitors farther away from racks or the generator, and that might fix the problem.

backup power generator

[President Chimp Toe]

How close is the backup power generator to your room? I think this could be the problem - due to EM inteference. A similar problem occurs if you have e.g. a large bass-box and you place the monitor next to it, which I hope you are no doing!

In fact, I have experienced exactly this where I work. There is a fscking great big generator right next door to me. My original monitor flickered like hell when I moved in to my new office. No matter what I did - where i put the monitor, whatever the settings, the flickering was completely unbearable.

The only way round the problem I have found is using a flat-screen. LCD doesnt suffer the same EM inteference problems as cathode ray. Hence no flickering.

Luckily I was able to find someone kind enough to swap monitors with, saving me some expense (my old CRT monitor was pretty darn huge and cool, though). Other than forking out for some new flat screen monitors, I dont know what to suggest!

UPS will help if it's not magnetic

[Snowfox]

A good UPS will help rectify current and voltage oscillation if it's not magnetic interference, which is the most likely cause if it's not magnetic interference.

But if you're going to lay out that kind of cash, replacing the monitors with cheap analog LCDs will make them immune to most kinds of interference and cut your power consumption significantly. Replacing them with digital LCDs (DVI-D) will make them work properly in the middle of a pile of supercharged magnets.

That said, I'd find someone who's comfortable throwing a scope on the line and checking out your power situation. If your building's UPS is throwing out an imperfect signal, it may be slowly killing your machines if left unrepaired. PCs don't take well to current variation or screwy spiked or squared voltage waveforms.

Good be power

[netringer]

I would check for power problems. I once had a similar situation, where you could actually hear something when the monitor screens would shrink a bit. One quiet night I figured out that it was the power hungry Sun SparcPrinter on the same power circuit that was firing up the fuser periodically. It was causing brown-outs.

If all of your flickering monitors are on the same circuit, or worse, the same surge protector, try changing that.

I have had surge protectors that were "used up" and were spiking the power on their own. Try taking the surge protectors out.

You might try monitoring the power voltage with a mulitmeter to see if you see a change when the flicker happens.

Try testing with a small online UPS for one monitor to see if that cures the problem. Note that it cannot be a standby UPS. Those won't cure brown outs. http://www.pcguide.com/ref/power/ext/ups/types.htm

You might try...

[OneFix]

Something like This. It might be cheaper to begin with and it's not another component to go bad :)

There are other similar products, but that should give you a good start.

Step by step

[maggard]

Summarized:

We've got funky electrical/magnetic problems going on in our office splace - any ideas?

1. Funky power is going to shorten the life of your hardware significantly. I used to work at a company where a series of IS servers "mysteriously" kept failing. When it became my turn to rebuild the fool thing I discovered it wasn't in our many-million-dollar server facility but down the hall from it, under a counter, plugged in next to a photocopier, big old laser printer and two fax machines. After discovering this and taking a look at the transients I'm was impressed they were lasting as long as they did. In your case hiding the problem with LCD displays isn't going to solve it.

2. On the other hand it could be lighting. Tube lighting flickers a lot and that can interact with the refresh rates on your monitors, particularly if you've all the same brand of monitors or your OS or staff keep setting them to the same refresh rates. Test this by adjusting the refresh rates of some monitors via software. Make one 65Hz, another 75Hz, if you can make another 85Hz. Also try working without the tube lighting. Get in some fill (torchier) and task (desklamp) lighting, preferably incandescent, and see if they obviate the problem.

3. So, if its not your eyes what devices are within 10m (same floor, floors above & below)? What devices are on the same circuits as your server? Are any of them motors, generators, heavy or intermittent draw devices? This includes laser printers, big fax machines, refrigerators, microwave ovens, etc. Survey all of this, ask your neighbors, ask to take a little tour for yourself, talk to the facilities folks.

4. Put servers on separate UPS's with power-line conditioning. It'll provide a backup to that generator (they know when to fail), clean up your supply, provide a bridge between the mains failing and the generator kicking in, just make everything a while lot more stable for your more expensive and critical hardware. Have purchasing get you a separate UPS/conditioner for each server and for heavens sake don't plug the monitors into them. If you really need server monitors when the power goes out get small flat-panel ones and plug them into their own UPSes (will give you handy spares you can sacrifice at need.) BTW these UPSes need not be power-all-day mondo models, just enough so that if that generator doesn't come on or there is some other problem they'll give everything time to shut down properly.

5. Replace the UPSes, "surge protectors" and the like every year or two. After enough hits the cheapie surge protectors become unresponsive and are essentially extension cords. The batteries on a UPS also age and start to loose charge faster. When you replace them migrate them down the critical path if you want but for heavens sake spray paint them, permanent marker them, something so they don't end up plugged into something really critical again.

6. Call an electrician. Seriously. 5 minutes with the hardware hanging from their belt and you'll have the comfort of knowing something. Also buy a compass, about US$15 or US$20 for a decent orienteering one. Walk it around the room to see if it shows any bobbles, it might help you track down the problem, or at least determine if the effect is strictly optical, electrical or there is a magnetic component too.

So between the time, services and hardware we're talking a few hundred bucks. Is that overkill? No way. That's popcorn compared to the disruption if one of your critical devices fails catastrophically, also nobody wants to work in a flickery environment. You wouldn't put up with a random "Feep" noise, why expect folks to deal with the visual equivalent? Staring at displays all day is tough enough without letting them degenerate into flickery ones.

Oh, and if nothing else works, remember the order of propitiation: Chicken, Goat, Virgin. If you ending up needing the last one call Corp HQ's IS, we usually have one or two on staff we could spare (we keep them just for this purpose.)