why can I not force this to run at 75mhz. The monitor can support it so, why the problem

**********************************************************************
# Monitor section
# **********************************************************************

# Any number of monitor sections may be present

Section "Monitor"

Identifier "Generic Monitor"
#Option "DPMS"

VertRefresh 50 - 70 # multisync
HorizSync 31.5 - 78

Modeline "1024x768" 81.80 1024 1080 1192 1360 768 769 772 802 -HSync +Vsync
Modeline "1024x768" 78.75 1024 1040 1136 1312 768 769 772 800
+hsync +vsync
Modeline "1024x768" 70 1024 1048 1184 1328 768 771 777 806 -hsync
-vsync
ModeLine "1280x800" 83.91 1280 1312 1624 1656 800 816 824 841
ModeLine "1600x900" 173.86 1600 1672 2032 2176 900 902 914 940 +hsync +vsync
Modeline "1280x720" 75 1280 1336 1472 1664 720 725 730 751
Modeline "1920x1080" 172.798 1920 2040 2248 2576 1080 1081 1084 1118 -hsync -vsync
Modeline "1920x1200" 193.156 1920 2048 2256 2592 1200 1201 1203 1242 +hsync +vsync
ModeLine "1366x768" 88.03 1366 1424 1680 1816 768 770 782 808
ModeLine "1088x612" 81.57 1088 1136 1376 1472 612 614 626 652 +hsync +vsync
ModeLine "1792x1344" 204.8 1792 1920 2120 2448 1344 1345 1348 1394 -hsync +vsync
ModeLine "1792x1344" 261.0 1792 1888 2104 2456 1344 1345 1348 1417 -hsync +vsync
ModeLine "1856x1392" 218.3 1856 1952 2176 2528 1392 1393 1396 1439 -hsync +vsync
ModeLine "1856x1392" 288.0 1856 1984 2208 2560 1392 1393 1396 1500 -hsync +vsync
ModeLine "1920x1440" 234.0 1920 2048 2256 2600 1440 1441 1444 1500 -hsync +vsync
ModeLine "1920x1440" 297.0 1920 2064 2288 2640 1440 1441 1444 1500 -hsync +vsync
ModeLine "1800x1440" 230 1800 1896 2088 2392 1440 1441 1444 1490 +HSync +VSync
ModeLine "1800x1440" 250 1800 1896 2088 2392 1440 1441 1444 1490 +HSync +VSync
Modeline "1280x768" 81.59 1280 1280 1384 1688 768 769 774 791

EndSection

# **********************************************************************
# Graphics device section
# **********************************************************************

# Any number of graphics device sections may be present

Section "Device"
Identifier "VESA"
Driver "nvidia" # do not remove vesa
#Option "XAANoOffscreenPixmaps"
Option "UseEDID" "FALSE"
Option "UseEdidFreqs" "FALSE"

EndSection


# **********************************************************************
# Screen sections.
# **********************************************************************

Section "Screen"

# The Identifier, Device and Monitor lines must be present

Identifier "Screen 1"
Device "VESA"
Monitor "Generic Monitor"
#Option "AddARGBGLXVisuals" "true"

# The favoured Depth and/or Bpp may be specified here

DefaultDepth 24

SubSection "Display"
Depth 32
ViewPort 0 0
Modes "1024x768" "1024x768"
EndSubsection

SubSection "Display"
Depth 16
ViewPort 0 0
Modes "1024x768" "1024x768"
EndSubsection

SubSection "Display"
Depth 24
ViewPort 0 0
Modes "1024x768" "1024x768"
EndSubsection


EndSection

Your telling X not to use the EDID information then providing too low a VertRefresh rate in the monitor section for it to be able to do 75 find the proper ranges for the monitor put them in there and restart the X server. BTW the modlines are probably not necessary at all X will use the highest setting possible with the values you give it.