Posted By Darren Honeyford Can anyone help, I have have been asked a question about the installation of new PC's, the screen's of these PC's keep having multiple flickers in this certain area, all the eletric's have been tested which are fine and other PC's currently in use elsewhere have been sited in this area with the same results as the new PC's. I have heard of eletomagnetic fields before but nothing in depth, any help would be much appreciated. Many Thanks Darren

Posted By Robert K Lewis Darren This problem only tends to occur where there are higher voltage cables than 240 volts. It is essentially the resultant mag. field induced by the current flow in the cables. This produces both distortion and/or flicker. Most competent electrical contractors can measure this field and design the appropriate screening around the cable. The other possibility is some piece of equipment that is within this area that is either producing changes in the local circuit or perhaps more rarely a magnetic field as a resultof its operation. It does need attention though if you intend to leave the PCs in the area as it is bad for the eyesight and can I believe induce underlying illnesses to respond eg Migraine headaches Bob

Posted By John Donaldson Have a look at whats on the other side of the wall, so to speak. If there is a switch room, plant room etc its possible that this could be causing the effect you mention. Even a small magnetic field is likely to cause problems. If the effect is transient it could be related to an item of equipment switching on and off. A boiler for example.

Posted By Bill Fisher Jim Whilst I understand the point you make the previous responses are all relevant and possible. My company buys its equipment from a national company (Dell) and I have experienced Mobile Phone interferance, magnetic interference from (eg) speakers too close etc. I am also aware of others who have been affected by the "room next door" scenarion. So whilst your reference to EEC and EMC is relevant, it does happen. Regards Bill

Posted By Ashley Williams Just an additional couple of suggestions: - Is this area under communications equipment e.g. Microwave transmitter or Mobile communications mast. You could even look at the buildings around you. One of my old civil service sites was opposit a police station and had similar problems. Have you tried altering the refresh frequency of the graphics cards from the the optimal setting? hope this might help Ashley