Cara,
vai lá no /etc/X11/xorg.conf
e troca suas seções "monitor" e " screen" por estas aí.
Section "Monitor"
Identifier "Monitor0"
Option "DPMS" "true"
# HorizSync 28.0 - 78.0 # Warning: This may fry very old Monitors
HorizSync 28.0 - 96.0 # Warning: This may fry old Monitors
VertRefresh 50.0 - 75.0 # Very conservative. May flicker.
# VertRefresh 50.0 - 62.0 # Extreme conservative. Will flicker. TFT default.
# Default modes distilled from
# "VESA and Industry Standards and Guide for Computer Display Monitor
# Timing", version 1.0, revision 0.8, adopted September 17, 1998.
# $XFree86: xc/programs/Xserver/hw/xfree86/etc/vesamodes,v 1.4 1999/11/18 16:52:17 tsi Exp $
# 640x350 @ 85Hz (VESA) hsync: 37.9kHz
ModeLine "640x350" 31.5 640 672 736 832 350 382 385 445 +hsync -vsync
# 640x400 @ 85Hz (VESA) hsync: 37.9kHz
ModeLine "640x400" 31.5 640 672 736 832 400 401 404 445 -hsync +vsync
# 720x400 @ 85Hz (VESA) hsync: 37.9kHz
ModeLine "720x400" 35.5 720 756 828 936 400 401 404 446 -hsync +vsync
# 640x480 @ 60Hz (Industry standard) hsync: 31.5kHz
ModeLine "640x480" 25.2 640 656 752 800 480 490 492 525 -hsync -vsync
# 640x480 @ 72Hz (VESA) hsync: 37.9kHz
ModeLine "640x480" 31.5 640 664 704 832 480 489 491 520 -hsync -vsync
# 640x480 @ 75Hz (VESA) hsync: 37.5kHz
ModeLine "640x480" 31.5 640 656 720 840 480 481 484 500 -hsync -vsync
# 640x480 @ 85Hz (VESA) hsync: 43.3kHz
ModeLine "640x480" 36.0 640 696 752 832 480 481 484 509 -hsync -vsync
# 800x600 @ 56Hz (VESA) hsync: 35.2kHz
ModeLine "800x600" 36.0 800 824 896 1024 600 601 603 625 +hsync +vsync
# 800x600 @ 60Hz (VESA) hsync: 37.9kHz
ModeLine "800x600" 40.0 800 840 968 1056 600 601 605 628 +hsync +vsync
# 800x600 @ 72Hz (VESA) hsync: 48.1kHz
ModeLine "800x600" 50.0 800 856 976 1040 600 637 643 666 +hsync +vsync
# 800x600 @ 75Hz (VESA) hsync: 46.9kHz
ModeLine "800x600" 49.5 800 816 896 1056 600 601 604 625 +hsync +vsync
# 800x600 @ 85Hz (VESA) hsync: 53.7kHz
ModeLine "800x600" 56.3 800 832 896 1048 600 601 604 631 +hsync +vsync
# 1024x768i @ 43Hz (industry standard) hsync: 35.5kHz
ModeLine "1024x768" 44.9 1024 1032 1208 1264 768 768 776 817 +hsync +vsync Interlace
# 1024x768 @ 60Hz (VESA) hsync: 48.4kHz
ModeLine "1024x768" 65.0 1024 1048 1184 1344 768 771 777 806 -hsync -vsync
# 1024x768 @ 70Hz (VESA) hsync: 56.5kHz
ModeLine "1024x768" 75.0 1024 1048 1184 1328 768 771 777 806 -hsync -vsync
# 1024x768 @ 75Hz (VESA) hsync: 60.0kHz
ModeLine "1024x768" 78.8 1024 1040 1136 1312 768 769 772 800 +hsync +vsync
# 1024x768 @ 85Hz (VESA) hsync: 68.7kHz
ModeLine "1024x768" 94.5 1024 1072 1168 1376 768 769 772 808 +hsync +vsync
# 1152x864 @ 75Hz (VESA) hsync: 67.5kHz
ModeLine "1152x864" 108.0 1152 1216 1344 1600 864 865 868 900 +hsync +vsync
# 1280x960 @ 60Hz (VESA) hsync: 60.0kHz
ModeLine "1280x960" 108.0 1280 1376 1488 1800 960 961 964 1000 +hsync +vsync
# 1280x960 @ 85Hz (VESA) hsync: 85.9kHz
ModeLine "1280x960" 148.5 1280 1344 1504 1728 960 961 964 1011 +hsync +vsync
# 1280x1024 @ 60Hz (VESA) hsync: 64.0kHz
ModeLine "1280x1024" 108.0 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
# 1280x1024 @ 75Hz (VESA) hsync: 80.0kHz
ModeLine "1280x1024" 135.0 1280 1296 1440 1688 1024 1025 1028 1066 +hsync +vsync
# 1280x1024 @ 85Hz (VESA) hsync: 91.1kHz
ModeLine "1280x1024" 157.5 1280 1344 1504 1728 1024 1025 1028 1072 +hsync +vsync
# 1600x1200 @ 60Hz (VESA) hsync: 75.0kHz
ModeLine "1600x1200" 162.0 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
# 1600x1200 @ 65Hz (VESA) hsync: 81.3kHz
ModeLine "1600x1200" 175.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
# 1600x1200 @ 70Hz (VESA) hsync: 87.5kHz
ModeLine "1600x1200" 189.0 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
# 1600x1200 @ 75Hz (VESA) hsync: 93.8kHz
ModeLine "1600x1200" 202.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
# 1600x1200 @ 85Hz (VESA) hsync: 106.3kHz
ModeLine "1600x1200" 229.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
# 1792x1344 @ 60Hz (VESA) hsync: 83.6kHz
ModeLine "1792x1344" 204.8 1792 1920 2120 2448 1344 1345 1348 1394 -hsync +vsync
# 1792x1344 @ 75Hz (VESA) hsync: 106.3kHz
ModeLine "1792x1344" 261.0 1792 1888 2104 2456 1344 1345 1348 1417 -hsync +vsync
# 1856x1392 @ 60Hz (VESA) hsync: 86.3kHz
ModeLine "1856x1392" 218.3 1856 1952 2176 2528 1392 1393 1396 1439 -hsync +vsync
# 1856x1392 @ 75Hz (VESA) hsync: 112.5kHz
ModeLine "1856x1392" 288.0 1856 1984 2208 2560 1392 1393 1396 1500 -hsync +vsync
# 1920x1440 @ 60Hz (VESA) hsync: 90.0kHz
ModeLine "1920x1440" 234.0 1920 2048 2256 2600 1440 1441 1444 1500 -hsync +vsync
# 1920x1440 @ 75Hz (VESA) hsync: 112.5kHz
ModeLine "1920x1440" 297.0 1920 2064 2288 2640 1440 1441 1444 1500 -hsync +vsync
# Additional modelines
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
# Extended modelines with GTF timings
# 640x480 @ 100.00 Hz (GTF) hsync: 50.90 kHz; pclk: 43.16 MHz
ModeLine "640x480" 43.16 640 680 744 848 480 481 484 509 -HSync +Vsync
# 768x576 @ 60.00 Hz (GTF) hsync: 35.82 kHz; pclk: 34.96 MHz
ModeLine "768x576" 34.96 768 792 872 976 576 577 580 597 -HSync +Vsync
# 768x576 @ 72.00 Hz (GTF) hsync: 43.27 kHz; pclk: 42.93 MHz
ModeLine "768x576" 42.93 768 800 880 992 576 577 580 601 -HSync +Vsync
# 768x576 @ 75.00 Hz (GTF) hsync: 45.15 kHz; pclk: 45.51 MHz
ModeLine "768x576" 45.51 768 808 888 1008 576 577 580 602 -HSync +Vsync
# 768x576 @ 85.00 Hz (GTF) hsync: 51.42 kHz; pclk: 51.84 MHz
ModeLine "768x576" 51.84 768 808 888 1008 576 577 580 605 -HSync +Vsync
# 768x576 @ 100.00 Hz (GTF) hsync: 61.10 kHz; pclk: 62.57 MHz
ModeLine "768x576" 62.57 768 816 896 1024 576 577 580 611 -HSync +Vsync
# 800x600 @ 100.00 Hz (GTF) hsync: 63.60 kHz; pclk: 68.18 MHz
ModeLine "800x600" 68.18 800 848 936 1072 600 601 604 636 -HSync +Vsync
# 1024x768 @ 100.00 Hz (GTF) hsync: 81.40 kHz; pclk: 113.31 MHz
ModeLine "1024x768" 113.31 1024 1096 1208 1392 768 769 772 814 -HSync +Vsync
# 1152x864 @ 60.00 Hz (GTF) hsync: 53.70 kHz; pclk: 81.62 MHz
ModeLine "1152x864" 81.62 1152 1216 1336 1520 864 865 868 895 -HSync +Vsync
# 1152x864 @ 85.00 Hz (GTF) hsync: 77.10 kHz; pclk: 119.65 MHz
ModeLine "1152x864" 119.65 1152 1224 1352 1552 864 865 868 907 -HSync +Vsync
# 1152x864 @ 100.00 Hz (GTF) hsync: 91.50 kHz; pclk: 143.47 MHz
ModeLine "1152x864" 143.47 1152 1232 1360 1568 864 865 868 915 -HSync +Vsync
# 1280x960 @ 72.00 Hz (GTF) hsync: 72.07 kHz; pclk: 124.54 MHz
ModeLine "1280x960" 124.54 1280 1368 1504 1728 960 961 964 1001 -HSync +Vsync
# 1280x960 @ 75.00 Hz (GTF) hsync: 75.15 kHz; pclk: 129.86 MHz
ModeLine "1280x960" 129.86 1280 1368 1504 1728 960 961 964 1002 -HSync +Vsync
# 1280x960 @ 100.00 Hz (GTF) hsync: 101.70 kHz; pclk: 178.99 MHz
ModeLine "1280x960" 178.99 1280 1376 1520 1760 960 961 964 1017 -HSync +Vsync
# 1280x1024 @ 100.00 Hz (GTF) hsync: 108.50 kHz; pclk: 190.96 MHz
ModeLine "1280x1024" 190.96 1280 1376 1520 1760 1024 1025 1028 1085 -HSync +Vsync
# 1400x1050 @ 60.00 Hz (GTF) hsync: 65.22 kHz; pclk: 122.61 MHz
ModeLine "1400x1050" 122.61 1400 1488 1640 1880 1050 1051 1054 1087 -HSync +Vsync
# 1400x1050 @ 72.00 Hz (GTF) hsync: 78.77 kHz; pclk: 149.34 MHz
ModeLine "1400x1050" 149.34 1400 1496 1648 1896 1050 1051 1054 1094 -HSync +Vsync
# 1400x1050 @ 75.00 Hz (GTF) hsync: 82.20 kHz; pclk: 155.85 MHz
ModeLine "1400x1050" 155.85 1400 1496 1648 1896 1050 1051 1054 1096 -HSync +Vsync
# 1400x1050 @ 85.00 Hz (GTF) hsync: 93.76 kHz; pclk: 179.26 MHz
ModeLine "1400x1050" 179.26 1400 1504 1656 1912 1050 1051 1054 1103 -HSync +Vsync
# 1400x1050 @ 100.00 Hz (GTF) hsync: 111.20 kHz; pclk: 214.39 MHz
ModeLine "1400x1050" 214.39 1400 1512 1664 1928 1050 1051 1054 1112 -HSync +Vsync
# 1600x1200 @ 100.00 Hz (GTF) hsync: 127.10 kHz; pclk: 280.64 MHz
ModeLine "1600x1200" 280.64 1600 1728 1904 2208 1200 1201 1204 1271 -HSync +Vsync
# 1920x1200 @ 60.00 Hz (GTF) hsync: 74.52; pclk: 193.16 MHz
Modeline "1920x1200" 193.16 1920 2048 2256 2592 1200 1201 1204 1242 -HSync +HSync
EndSection
Section "Device"
Identifier "Card0"
Driver "vesa"
# BusID "PCI:2:0:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
DefaultColorDepth 24
SubSection "Display"
Depth 1
Modes "1280x960" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x800" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x800" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x800" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x800" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x800" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 32
Modes "1280x800" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
EndSection
Bom, isso vai resolver o problema da configuração, mas não da placa de vídeo, ainda vai ser muito dificil voce usar o compiz.
Valeu