Waves going down monitor - dual setup

[mikeyboy714]

I recently got a second 17" LCD monitor and hooked it up to my MSI 6600GT. However, I noticed that when they are both on, one of them (the new one, Samsung 712N) started showing waves of darkness going down, kinda like you see when they show a computer monitor on TV. I've always assumed that it was due to a refresh rate mismatch. However, in this case the waves disappear when I turn off the secondary monitor, and the waves get better (I think really just smaller and faster so that it's hard to see) when I decrease the refresh rate to 60Hz. I've set both of them to 1280x1024@60Hz right now and it's usable, but on some screens you still see the waves going down.

Anyone know how I might go about fixing this?

 

[Matthias99]

Originally posted by: mikeyboy714
I recently got a second 17" LCD monitor and hooked it up to my MSI 6600GT. However, I noticed that when they are both on, one of them (the new one, Samsung 712N) started showing waves of darkness going down, kinda like you see when they show a computer monitor on TV. I've always assumed that it was due to a refresh rate mismatch. However, in this case the waves disappear when I turn off the secondary monitor, and the waves get better (I think really just smaller and faster so that it's hard to see) when I decrease the refresh rate to 60Hz. I've set both of them to 1280x1024@60Hz right now and it's usable, but on some screens you still see the waves going down.

Anyone know how I might go about fixing this?

Hmm... could be a noisy power issue. Do they still do it if you move them (physically) further apart on your desk? If so, maybe try plugging them into different electrical circuits, or at least not on the same outlet?

Also, if the new monitor is on VGA, you may be getting EMI in the area from another device (that you're just not noticing on the first monitor since it uses DVI and is largely immune to such interference). Move anything with an electrical motor (fans, etc.), or that draws a lot of power (space heaters, refrigerators, etc.) physically away from the monitors, and make sure they are on a different electrical circuit.

 

[mikeyboy714]

I tried plugging it into a different outlet and still have the same problem. Then I tried a few different setups.
Monitor 1: Samsung 712N
Monitor 2: Cornea MP704
DVI = Plugged into DVI port, through the DVI->VGA adapter
VGA = Plugged into VGA port

1->VGA, 2->DVI ==> waves
1->DVI, 2->VGA ==> waves
1->DVI only ==> no waves
1->VGA only ==> no waves
1->VGA, 2->Laptop ==> no waves

It's not the monitor itself, since it works fine alone. It's not power, since even if both are on with the Cornea connected to the VGA-out of my laptop, I don't see waves. Moving them farther apart doesn't help either.

Based on this I have to assume it's some kind of incompatibility between my monitor and my video card's dual display mode? It doesn't look like the video card itself, either, since it occurs on the same monitor every time, not the same port. I don't *see* any waves on my Cornea, maybe they are there but if they are it's too faint or too fast for me to catch it.

Any other ideas?

 

[Peter]

The two signals might be interfering right on the VGA card.

 

[mikeyboy714]

Originally posted by: Peter
The two signals might be interfering right on the VGA card.

Would this cause the waves to stay only on one monitor though? It would make sense that the interference is coming on the card if the same port always produced the distortion, but the Cornea monitor never shows any signs.

 

[mikeyboy714]

Just following up, I haven't fixed the problem, but I "borrowed" another Samsung 712N and hooked it up and didn't have any problems. It looks like it was the Cornea which is causing problems, but I have no idea why. Separately, they work fine. I'm about ready to give up unless someone else has another idea.

 

[yhelothar]

I just to get this with my dual monitor setup. After a while it just went away, don't know why or how.