We found the following in the Technical Information Library using "monitor and
interference" as a search string:
Apple Two-Page Monochrome Monitor: Images Vibrate
Interference between two monitors placed side-by-side can cause images on the
monitors to vibrate. The reason is that, when placed side-by-side, monitors
can magnetically interfere with each other, causing the image on one or both
monitors to appear to vibrate slightly. This interference problem is most
often seen when an RGB color monitor is placed next to a large-screen
monochrome monitor. The amount of interference can also vary depending on the
user's environment.
Moving the monitors further apart, especially the rear ends, usually reduces
the vibration effect.
Technical Reason For Picture Vibrating
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The cause of this shimmering effect lies in the vertical refresh rate, the
number of times a monitor repaints the screen each second. When this rate
differs significantly between monitors, the interference described above can
occur. There is often a large difference between RGB and monochrome monitors.
Thus, the vibration effect most often occurs with this combination. Because
other factors are involved, it is possible for two monitors with the same
refresh rate to exhibit this effect, although this is less frequent.
Shielding monitors so as to prevent this type of interference would add a great
deal to the cost of each monitor. Further, by shielding a monitor you can
prevent the monitor from interfering with other monitors, but other monitors
could still interfere with it. Apple is investigating a number of technologies
to prevent this interference in the future and plans to incorporate them as
they become feasible.
We are sorry that we cannot solve your problem at this time, but you may see an
improvement if:
- the orientation of the monitors is reversed
- the monitors are separated by 8-10 inches
- a metallic plane (foil-wrapped cardboard, for example) is placed between the
monitors.