Monitor Problems...

[gyoung]

I've got an issue with my monitor. I recently moved my PC to the basement (den). Ever since then the monitor looks as though the refresh rate is at 60hz (screen flicker) on the upper left-hand portion of the screen even though it is set to 100hz. It comes and goes periodically spreading through to the entire left side of the screen. Looks more like interference than anything.

Here's what I tried during my troubleshooting.

Attached is a diagram of the room. PC1 is the PC I just moved, on the other side of the wall in the unfinished basement I have a server that is working fine (PC2 in the diagram). No problem with the monitor.

1st theory: Monitor going bad: I moved the monitor to PC2's location it didn't have any problems. I hooked up a PC2s monitor to the PC1 CPU and it did the same thing.

2nd theory: Video card: So this led me to believe that it isn't the monitor. I switched video cards from PC1 (Radeon 7200) to PC2 (Matrox G450) and the video card in PC2's location was fine, but PC1's location had the same problem.

A collegue of mine mentioned that the nearby furnace may be the problem. It is an old furnace and he said it could have magnetic coils in it that are unshielded and they could be causing the problem. He mentioned it because I told him that whent he furnace kicks in (fires up) the distortion gets even larger for a second which inclines me to think he's right. But wouldn't the problem be occurring in PC2's location also. The PCs are so close together, only separated by paneling. Or could it be that the furnace's magnetic coils are that finely directional?

Is there a way to test for this type of interference? Or am I out of luck?

[wallie_x]

By your diagram I'd say your friend's theory is the most likely culprit. Try shielding the monitor (and the computer) from the furnace. Or it could also be the strong EMF created by the wiring leading to the furnace, and (or) the power fluctuations it creates when it turns on.

[gyoung]

Anything handy around that house that would act as a shield that I could test the theory? I don't have too many lead vests lying around.

[wallie_x]

Question: The upper left hand corner of your monitor points to where? Toward the furnace or to wiring that leads to the furnace?

I believe wood is a good insulator, but not the best. Double cardboard with tin foil on one side, the aluminum pointing toward the EMF source, but kept at least 10" away from what's being shielded (for experimental purposes only). If its the wiring this might not work.

Does the furnace run on 220v per chance?

[John Prophet]

100hz???? Could that be the issue?? Thats a lot of strain on a monitor..have you tried, say 75 or 80hz??

[gyoung]

Question: The upper left hand corner of your monitor points to where? Toward the furnace or to wiring that leads to the furnace?

Toward the furnace. I would have to check and see where the wiring is located. How would I check to see if it is on 220v? The gas furnace is over 40 years old. When we bought the house the inspector said that it would last for another 40 years and that the manufacturer made a mistake in designing such a reliable furnace. Not the most efficient, but it has been durable.

100hz???? Could that be the issue?? Thats a lot of strain on a monitor..have you tried, say 75 or 80hz??

Yeah, I knocked it down to 85hz and 75hz, same problem. I've taken the monitor as a problem out of the equation. It is due to the location. The problem is that the location is ideal for placing the computer. If I can shield it that would be great. The last alternative is to either move the desk to the other side of the room or to buy an LCD monitor.

[wallie_x]

220v equals BIG wiring (> 18ga.) and a funny looking plug that resembles an electric dryer.

[gyoung]

I'll have to take a look when I get home. There is one of those plugs on the other side of the basement, so it may be.