Electrical interferance.

[The PIT]

Somewhere or somewhere in our house or our neighbours house is something thats creating a lot of electrical interferance. The end result I've got two monitors that will shimmer sometimes. Bloody annoying.

[SteveC]

Fridge or Freezer on the same electrical mains ring?

[The PIT]

Shouldn't be. Anyway the mains line is filtered.
Could well be the eight fans have in the case thats doing it.

[impact]

What are you doing? Building a helicopter?

"ROGER THAT DISPATCH! LIFTING OFF FROM THE HELIPORT!"

[The PIT]

Sounds like it sometimes. I'm looking at some of those fans that automatcially adjust there speed depending on the case temp.
I'll have to move the case further away from the computer and see what happens.
Also when I get the chance I'll turn off the power downstairs and see what happens.

[The PIT]

Interesting I've got another computer in the room and I stuck that at same resolution (1280 x 1240) as my new monitor and it shimmied like mad. There three feet apart so shouldn't interfer which each other.
Dropping down from the resolution and the shimmering disappears. Odd.
I know it's not the monitors or the graphics cards. Ones a G550 and the others a Radeon 8500. Power supplies are the same and the motherboards are both Epox 8kha and 8kha+ respectively.

[DrMark]

What refresh rate are you using?

As for the mains "filtering" I would not rely on this being 100% effective, it will have a bandwidth over which it is effective, anything outside this range can still cause trouble.

One thing to check is the quility of the neutral connection on your monitors, make sure plugs are clean etc. I high resistance to ground (neutral in this case) increases a devices suceptability to EMC problems. How old is the wiring in your house?

Cheers
Mark

[The PIT]

It has been rewired but some time ago. Only one computer is filtered and that is done twice. The interferance range varies a bit I once disposed of it on one of the monitors by going to 90hz. The next day it was the worse it has been. I run at 85hz because the image on both monitors is at it's best after that the focus starts going. I've still noticed slight shimmering at 120hz. You've got too look hard though.
I've just got to move things around. I'm also going to borrow my base unit from work. If that doesn't do it then we're looking at either case fans or dodgy Epox boards / Powersupply. I know some Epoxs and the DVI on radeons 8500 don't get on.

[[Ch]amsalot]

Join the club, Pit.

I've heard wrapping the monitor up in tin-foil (save for the vents) may help. I'll try it next time it gets bad and let you know the results.

-[Ch]ams

[The PIT]

It's annoying isn't it. I've also seen similar stuff at work where one room in the building was effected. If the epox was known for it's problems with DVI and radeon 8500 I would very likely have gone for a LCD screen. I thought LCD £800 quid then perhaps new motherboard err no.

[The PIT]

Well I just moved one of the monitors in the room and still the same interferance. I switched off our boiler and the fridge was off doing nothing and still the same.
I wonder if it's crap wiring.