View Full Version : 15" montier unusable at 1024x768

21-01-2006, 05:35 PM
because of the insanely high frequencys it outputs at 1024x768 its unusable since i feel sickened.
i have another one which works fine, so thats all good, but eventually ill want to have both of them and my 17" monitor hooked up to a 6600 and 5200 so ill have to either find anotehr 15" moniter or a 17"(more money) or get the 15" monteir to stop making noises.

also at 1280x1024 my 17" is running at 60hz. and my 15" are both runnign at 60hz at 1024x768 which makes a black bar go down the screen of teh 17"
the furtehr away it is the less this is pronounced. but i can only move it abuot 15-20cm, and at that distance spanning content across them seems unnatural. if i have them side by side the line is quite boldand moves quite quickly. ive just noticed when seeing how bold it is close togetehr that there is now a line of teh 15" which is goign up.

i read somewhere that this interference is caused by the displays not having adiquet sheilding.
how would i go about improving the sheilding, and what can i do to reduce the sound my montier makes at 1024x768.
also 60hz at 1280x1024 on the 17" is the highest it can go, same for the 15" at 1024x768.
on a side note, both 15" montiers are compaq branded moniters from the mid 90s, the good one was made in december 1995 and the annoying one was made in october 1995. i got these from my dads work last year (customs)

Speedy Gonzales
21-01-2006, 05:41 PM
And I take it you've installed the driver/s for the 5200 and 6600?

21-01-2006, 06:13 PM
Old monitors (very!)

Yes they will interfere with each other, that's the nature of old poorly shielded monitors.

The picture results from an electron beam that is swept across and up and down the screen by electro-magnetic coils, they are not limited to just the beam though, in unshielded monitors they extend outwards into the next-door monitor.

Buy a pair of LCD's, then you will not have the problem.

Sheilding costs would likely well exceed that of a new monitor.

And 1024 x 768 was fairly rare in '95...., I am surprised the monitor has not self destructed! It is probably operating outside of its design parameters

21-01-2006, 06:23 PM
i havent brought the 5200 yet, planning to within a few months.

the 17" monitor is abuot 2-3 years old.
and the 15" moniters are the exact same model, i dont see why one works fine while the other one makes the high pitched noises.
woudlt wrapping it in tinfoil reduce the interference?
also, as much as id love to have 2 17" moniters on either side of my 17" crt, im broke so they are kinda out of the question.

21-01-2006, 06:41 PM
woudlt wrapping it in tinfoil reduce teh interference?

Have you never noticed that tinfoil is completely unaffected by magnets ... ?
It's aluminium, not steel. You need a ferrous metal to block magnetic effects.

A sheet of 3mm steel between the two monitors may have an effect, but tinfoil will not.

21-01-2006, 06:50 PM
Interference is a pain but something you have to put up with. I've got dual monitors and have found that they pretty much have to be exactly the same model in order to keep those lines out of the way (for some reason they sometimes have small variations in freq.). Its quite interesting because the speed the bar goes down the screen can be used to find the difference in frequency between the refresh rates of the monitors.

By chance are the monitors those crapola 15" phillips ones. A place I worked at bought a butt-load of them and they were quite possibly the worst thing ever put out by phillips. Ever. 60Hz is bad for the eyes, 75Hz is probably the minimum . Avoid the headaches and screwing you eyes over, it'll be cheaper in the long run.

21-01-2006, 06:59 PM
ill check.


no clue if phillips made them

21-01-2006, 07:20 PM
i was just poking around in the nvidia drivers and the 17" at 1280x1024 has a horizontal scan rate of 63.97 kHz and a vertical refresh rate of 60.014Hz
while the 15" @1024x768 has a horizontal scan rate of 48.36kHz and a Vertical Refresh rate of 60.003Hz (this is the happy display). im goign to swap the 15" screens over to get an idea of what teh timings on the other screen is. this is under the advanced timings section of the Nview driver toolset thingy.
there doent seem to be a difference between thge 2 15" screens, and ouch i just had to turn it off, it started off quietly and then just got stronger and stronger till it was jsut too much.

22-01-2006, 01:09 PM
Seriously, a higher resolution is not worth the pain of 60Hz. Your eyes will hate you very soon, drop the resolution!

23-01-2006, 05:28 AM
ibe been using 1280x1024@60hz on the 17" for like well, ever since i set it to that resolution whihc only took a coulpe of weeks., so that was like ~2 years ago,

Billy T
23-01-2006, 06:20 PM
It is possible to operate two conflicting monitors side by side provided that they are both set to the same refresh rate and are operating off the same computer.

I rarely disagree with GF, but actually it is possible to economically shield them from each other using a simple three layer shield made of two pieces of 0.5-1mm steel (of pretty much any specification) with a 1mm layer of aluminium between them.

The steel will shield the magnetic fields to a certain extent, and the aluminium will provide both an "air" gap between the steel sheets, and the higher refresh frequencies will induce eddy currents in the aluminium which will generate opposing polarity electromagnetic fields which will help cancel out the interference.

The focal point for the interference source is the rear of the CRT where the scan coils are located, so I would make a shield that is the height of the monitor and about the same depth as the front to rear dimension.

Allow the shield to protrude about 5cm past the rear of the monitors (the front isn't the problem) and is residual interference is present, separate the monitors by a couple of cm.

If you want to experiment, just a plain sheet of thin steel (say .25 to 1mm, not 3mm) might even be enough to sort it for you. The field source is very localised.


Billy 8-{)