Quadra 840AV: Using With NEC Multisync 6FG

I have an NEC MultiSync 6FG monitor. With a Macintosh Quadra 840AV, it works fine in 640 x 480 mode, but not 1152 x 870. It acts like it's not syncing correctly.
A Quadra 840AV connected to an NEC MultiSync FG 21-inch 6FG monitor requires the new AV 1152 X 870 or AV Multi-Res adapter. To obtain these adapters free of charge from NEC, call 312-622-7427. (General NEC Tech Support questions should be directed to 800-388-8888.)
Published Date: Feb 19, 2012