Many VGA LCDs only sync @ 60Hz, which is a problem with many Macs which don't put out a 60Hz resolution. MultiSync type LCDs work with traditional Mac resolutions/sync rates.

You've got me curious about your report on the Q605:

re. the 605 said:

video: 512 KB VRAM, expandable to 1 MB (remove both 256K VRAM SIMMs, plug in 512K replacements; supports 512 x 384, 640 x 480, 640 x 870, 832 x 624, 1024 x 768, and 1152 x 870 resolutions. We have a field report of an 800 x 600 option as well.

Click to expand...

Did you try running it at 800 x 600?

As for 1024 x 768 @ 75Hz, Macs can run this @ 60, 67 & 75 Hz rates, depending on the Mac. Some will output @ 75Hz while others won't IIRC. A lot depends upon when the Mac was introduced. VGA and Mac resolutions/sync rates developed in parallel, converging as time passed. In much of the 68k Mac history, 60Hz was considered flickery on a CRT, which isn't an issue for LCDs. By the Quadra era VGA resolutions began to be supported by Macs.

edit: has anyone got a link to Mac resolution/scan rate chart? The closest thing I could find online was:

http://home.earthlink.net/~gamba2/vid-mon-matrix.html (bottom of page)