Я безуспешно пробовал разные способы, но нашел решение, пока решал другую проблему:
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.bak
Если файл не существует:
sudo nano /etc/X11/xorg.conf
Добавьте следующий контент:
Section "Device"
Identifier "ATI Radeon"
Driver "ati"
Option "AccelMethod" "EXA"
Option "MigrationHeuristic" "greedy"
Option "AccelDFS" "true"
Option "EnablePageFlip" "true"
Option "EnableDepthMoves" "true"
EndSection
Section "Monitor"
Identifier "Configured Monitor"
Vendorname "Samsung"
Modelname "Samsung SyncMaster 793S/793V/CM173G"
Horizsync 30-71
Vertrefresh 50-160
modeline "640x480@60" 25.2 640 656 752 800 480 490 492 525 -vsync -hsync
modeline "640x480@72" 31.5 640 664 704 832 480 489 491 520 -vsync -hsync
modeline "640x480@75" 31.5 640 656 720 840 480 481 484 500 -vsync -hsync
modeline "640x480@85" 36.0 640 696 752 832 480 481 484 509 -vsync -hsync
modeline "800x600@56" 36.0 800 824 896 1024 600 601 603 625 +hsync +vsync
modeline "800x600@72" 50.0 800 856 976 1040 600 637 643 666 +hsync +vsync
modeline "800x600@75" 49.5 800 816 896 1056 600 601 604 625 +hsync +vsync
modeline "800x600@85" 56.3 800 832 896 1048 600 601 604 631 +hsync +vsync
modeline "800x600@60" 40.0 800 840 968 1056 600 601 605 628 +hsync +vsync
modeline "832x624@75" 57.284 832 864 928 1152 624 625 628 667 -vsync -hsync
modeline "1024x768@85" 94.5 1024 1072 1168 1376 768 769 772 808 +hsync +vsync
modeline "1024x768@75" 78.8 1024 1040 1136 1312 768 769 772 800 +hsync +vsync
modeline "1024x768@70" 75.0 1024 1048 1184 1328 768 771 777 806 -vsync -hsync
modeline "1024x768@60" 65.0 1024 1048 1184 1344 768 771 777 806 -vsync -hsync
modeline "1024x768@43" 44.9 1024 1032 1208 1264 768 768 776 817 +hsync interlace +vsync
modeline "1152x864@75" 108.0 1152 1216 1344 1600 864 865 868 900 +hsync +vsync
modeline "1280x960@60" 102.1 1280 1360 1496 1712 960 961 964 994 -hsync +vsync
modeline "1280x1024@60" 108.0 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
modeline "1400x1050@60" 122.61 1400 1488 1640 1880 1050 1051 1054 1087 -hsync +vsync
Gamma 1.0
EndSection
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "ATI Radeon"
Defaultdepth 24
SubSection "Display"
Depth 24
Modes "1024x768@70" "1024x768@60" "1024x768@75" "1024x768@43" "1024x768@85"
"1152x864@75" "832x624@75" "1280x960@60" "800x600@60" "1280x1024@60"
"800x600@85" "1400x1050@60" "800x600@75" "800x600@72" "800x600@56"
"640x480@85" "640x480@75" "640x480@72" "640x480@60"
EndSubSection
EndSection
Теперь startx
и оно должно работать ...