Su Ubuntu 7.10, con monitor Mitsubishi Diamond pro2040u, driver fglrx.
Avevo una risoluzione di 1920x1440, ma il refresh era troppo basso e andavo via di testa. Cosi' ho cercato il monitor specifico da System>Administration>Screen and Graphics, l'ho trovato, ho impostato risoluzione, refresh, riavviato e X non partiva piu'. Ho aperto un terminale, ho fatto dpkg-reconfigure xserver-xorg mettendo i parametri che ho trovato sul manuale del monitor:
...horizontal scan frequencies between 30kHz and 121kHz, and vertical scan
frequencies between 50Hz and 160Hz.
e anche le corrette risoluzioni supportate.
Ora, questo e' il mio Xorg.conf
codice:
Section "Files"
EndSection

Section "InputDevice"
	Identifier	"Generic Keyboard"
	Driver		"kbd"
	Option		"CoreKeyboard"
	Option		"XkbRules"	"xorg"
	Option		"XkbModel"	"pc105"
	Option		"XkbLayout"	"us"
EndSection

Section "InputDevice"
	Identifier	"Configured Mouse"
	Driver		"mouse"
	Option		"CorePointer"
	Option		"Device"	"/dev/input/mice"
	Option		"Protocol"	"ImPS/2"
	Option		"ZAxisMapping"	"4 5"
	Option		"Emulate3Buttons"	"true"
EndSection

Section "InputDevice"
	Driver		"wacom"
	Identifier	"stylus"
	Option		"Device"	"/dev/input/wacom"
	Option		"Type"	"stylus"
	Option		"ForceDevice"	"ISDV4"# Tablet PC ONLY
EndSection

Section "InputDevice"
	Driver		"wacom"
	Identifier	"eraser"
	Option		"Device"	"/dev/input/wacom"
	Option		"Type"	"eraser"
	Option		"ForceDevice"	"ISDV4"# Tablet PC ONLY
EndSection

Section "InputDevice"
	Driver		"wacom"
	Identifier	"cursor"
	Option		"Device"	"/dev/input/wacom"
	Option		"Type"	"cursor"
	Option		"ForceDevice"	"ISDV4"# Tablet PC ONLY
EndSection

Section "Device"
	Identifier	"ATI Technologies Inc Radeon R300 ND [Radeon 9700 Pro]"
	Boardname	"ati"
	Busid		"PCI:1:0:0"
	Driver		"ati"
	Screen	0
	Option		"MergedFB"	"off"
EndSection

Section "Monitor"
	Identifier	"Mitsubishi Diamond Pro 2040u"
	Modelname	"Custom 1"
  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  "1280x1024@75" 135.0 1280 1296 1440 1688 1024 1025 1028 1066 +hsync +vsync
  modeline  "1280x960@60" 102.1 1280 1360 1496 1712 960 961 964 994 -hsync +vsync
  modeline  "1280x960@85" 148.5 1280 1344 1504 1728 960 961 964 1011 +hsync +vsync
  modeline  "1280x1024@85" 157.5 1280 1344 1504 1728 1024 1025 1028 1072 +hsync +vsync
  modeline  "1280x1024@60" 108.0 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
  modeline  "1280x960@75" 129.86 1280 1368 1504 1728 960 961 964 1002 -hsync +vsync
  modeline  "1400x1050@60" 122.61 1400 1488 1640 1880 1050 1051 1054 1087 -hsync +vsync
  modeline  "1400x1050@75" 155.85 1400 1496 1648 1896 1050 1051 1054 1096 -hsync +vsync
  modeline  "1600x1200@65" 175.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
  modeline  "1600x1200@60" 162.0 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
  modeline  "1600x1200@75" 202.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
  modeline  "1600x1200@70" 189.0 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
  modeline  "1600x1200@85" 229.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
  modeline  "1792x1344@75" 261.0 1792 1888 2104 2456 1344 1345 1348 1417 -hsync +vsync
  modeline  "1792x1344@60" 204.8 1792 1920 2120 2448 1344 1345 1348 1394 -hsync +vsync
  modeline  "1856x1392@60" 218.3 1856 1952 2176 2528 1392 1393 1396 1439 -hsync +vsync
  modeline  "1856x1392@75" 288.0 1856 1984 2208 2560 1392 1393 1396 1500 -hsync +vsync
  modeline  "1920x1440@60" 234.0 1920 2048 2256 2600 1440 1441 1444 1500 -hsync +vsync
  modeline  "1920x1440@75" 297.0 1920 2064 2288 2640 1440 1441 1444 1500 -hsync +vsync
  modeline  "2048x1536@60" 266.95 2048 2200 2424 2800 1536 1537 1540 1589 -hsync +vsync
  modeline  "2048x1536@75" 340.48 2048 2216 2440 2832 1536 1537 1540 1603 -hsync +vsync
	Gamma	1.0
EndSection

Section "Screen"
	Identifier	"Default Screen"
	Device		"ATI Technologies Inc Radeon R300 ND [Radeon 9700 Pro]"
	Monitor		"Mitsubishi Diamond Pro 2040u"
	Defaultdepth	24
	SubSection "Display"
		Depth	24
		Virtual	2048	1536
		Modes		"1920x1440@75"	"2048x1536@60"	"1920x1440@60"	"2048x1536@75"	"1856x1392@75"	"1856x1392@60"	"1792x1344@60"	"1792x1344@75"	"1600x1200@85"	"1600x1200@70"	"1600x1200@75"	"1600x1200@60"	"1600x1200@65"	"1400x1050@75"	"1400x1050@60"	"1280x960@75"	"1280x1024@60"	"1280x1024@85"	"1280x960@85"	"1280x960@60"	"1280x1024@75"	"1152x864@75"	"1024x768@43"	"1024x768@60"	"1024x768@70"	"1024x768@75"	"1024x768@85"	"832x624@75"	"800x600@60"	"800x600@85"	"800x600@75"	"800x600@72"	"800x600@56"	"640x480@85"	"640x480@75"	"640x480@72"	"640x480@60"
	EndSubSection
EndSection

Section "ServerLayout"
	Identifier	"Default Layout"
  screen 0 "Default Screen" 0 0
	Inputdevice	"Generic Keyboard"
	Inputdevice	"Configured Mouse"
	
	# Uncomment if you have a wacom tablet
	#	InputDevice     "stylus"	"SendCoreEvents"
	#	InputDevice     "cursor"	"SendCoreEvents"
	#	InputDevice     "eraser"	"SendCoreEvents"
EndSection
Section "Module"
	Load		"v4l"
EndSection
Section "device" # 
	Identifier	"device1"
	Boardname	"ati"
	Busid		"PCI:1:0:0"
	Driver		"ati"
	Screen	1
	Option		"MergedFB"	"off"
EndSection
Section "screen" # 
	Identifier	"screen1"
	Device		"device1"
	Defaultdepth	24
	Monitor		"monitor1"
EndSection
Section "monitor" # 
	Identifier	"monitor1"
	Gamma	1.0
EndSection
Section "ServerFlags"
EndSection
Ma nelle risoluzioni selezionabili poi non esiste 1920x1440 ma 1920x1200, che quindi e "stretchata". Ma dico io, da dove gli viene quella cxxxo di risoluzione??