View Full Version : Anything wrong with 2 monitors next to each other?

14-11-2003, 08:39 AM
I have 2 computers at the same desk, and the monitors are close by, maybe 20 cm apart.

When one is on, and I turn the other on, the other monitor goes nuts for a second, sort of like that deguass thing.

Is this going to reck the monitors?

14-11-2003, 08:52 AM
sounds like you might have some older noisy monitors, i have two monitors touching each other and they are fine and dandy, but another guy i know put some together and he was getting scrolling lines runing up and down them all the time.

Dont know if it will cause permenant damage, but you could always try to put a thin steel sheet between them to stop EMI.


14-11-2003, 09:01 AM
It shouldn't cause permanent damage, because AFAIK, all that is happening is the monitors are affecting each others electromagnetic field (or something like that).

14-11-2003, 09:56 AM
Sometimes monitors can happily reside next to each other and other times they can't. It seems to depend on the quality and the amount of sheilding present.

Have a play around with different refresh rates and screen resolutions, some screens deguass as they turn on and that will impact a screen in close proximity.

I have 2 compaq screens on my work PC and they play happily, however a compaq and philips on my home PC couldn't get along next to each other .... eventually I found a combination of resolutions and refresh rates that worked together.

14-11-2003, 10:00 AM
Should I have a thin sheet of steel between the monitor and my head also?

Chemical Ali
14-11-2003, 10:34 AM

Carefully glue the thin steel sheet to your head BEFORE sitting down in front of your monitor.........

14-11-2003, 11:07 AM
Can I have holes for my eyes, or do they have to be covered too?

14-11-2003, 11:18 AM
No, I prefer riveting the steel to the front of the monitor, that way the radiation is stopped before it gets past the monitor.

14-11-2003, 11:27 AM
Maybe they should start making monitors with steel behind the glass for extra safety.

14-11-2003, 11:30 AM
That's what LCDs are for, I think :D

With TVs, you shouldn't really sit closer than three metres because of the radiation emitted, but computer monitors are different. Still emit radiation, but not nearly as much as TVs.

14-11-2003, 01:46 PM
Where the 2 monitors each with it's own spike guard are fed from the same wall plug if you start the 2nd monitor whilst the first is booting up the power surge can result in the first boot getting all upset and calling it a day

Billy T
14-11-2003, 03:30 PM
The effect you are seeing is quite normal and is the degauss field from the start-up monitor affecting the screen that is already up and running.

Provided they are both running at the same refresh rate there will be no problems, however differential refresh rates will produce visible interference effects at the difference frequency between the two refresh settings.

For example, if one is set to 60Hz and the other is on 75Hz there will be a 15Hz interference pattern on one or both monitors, usually in the form of horizontal black lines moving up or down the screen but other effects can happen. The cause is electromagnetic interaction between the scanning fields in each monitor.

I disagree with FrankS' comment re shared power outlets, because if starting one computer interrupts the boot on another then there is a serious issue with the supply impedance, i.e. loose wiring connections, spread pins in the socket or corroded fuse holders.

Surge protectors are irrelevant to this issue as they are intended to protect against voltage increases, not voltage drops or load current surges. Only a UPS can protect against voltage drops, and nothing really protects against momentary load current surges, except perhpas a UPS if the current peak is high enough to lower the voltage to the point where the UPS kicks in. Again, it shouldn't have any effect if the supply wiring and connections are up to scratch.

Don't use cheap multiway boxes to supply power though, they can be very high impedance.


Billy 8-{)

14-11-2003, 03:49 PM
Ok, they are not the same. In linux, how do you change the refresh rate? I can do the resolution, but not the refresh rate.

14-11-2003, 06:01 PM
Agree surge protectors irrelevant but mentioned it in case someone queried if they were fitted, don't have any loose wires etc as I am very fussy about that, re the multiway box that could be the culprit, will change it and see if it makes any difference.

14-11-2003, 06:31 PM
> Ok, they are not the same. In linux, how do you
> change the refresh rate? I can do the resolution, but
> not the refresh rate.

You need to make sure the monitor running X supports the refresh rate you want to change to first.

Terry Porritt
14-11-2003, 09:54 PM
Thin sheet steel rivetted to the screen or to your head is not the best material to screen magnetic fields from your brain :) What you need is or mu metal. This is a special alloy that is used to screen oscilloscope tubes from extraneous magnetic fields that would cause distortion to a precision display.

15-11-2003, 02:14 AM