figured out the clock and vertical and horizontal timings for the 90C31
"640x480" 25.2 640 664 912 800 480 490 502 523
"800x600" 28.3 800 840 984 1024 600 600 610 623
"1024x768" 63.478 1024 1048 1248 1264 384 383 386 407
I put an Xconfig file with these values at sunsite.unc.edu
Jesus Chrysler