The Apple Portrait Display is a known source of OUTRAGEOUS amounts of RFI, which usually show up as vertically rolling bands on any (Color?) Monitor within cat swinging distance. I had to put a grounded piece of Galvanized Sheet Metal between my (Radius OEM'd) APD and my Radius PrecisionView 2150 to keep the rolling bands at bay.

The towers are not at fault, it's the combination of monitors that'll drive you up the wall. The old Radius Two Page Display (Grayscale) is from the same era as the APD/Radius FPD and so is probably shielded adequately from its skinnier Siblings.