OK, weitere Infos:
$ xrandr --prop
Screen 0: minimum 320 x 200, current 2560 x 1440, maximum 16384 x 16384
DisplayPort-0 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 553mm x 311mm
EDID:
00ffffffffffff0010ac6ed04c343731
041b0104a5371f783e4455a9554d9d26
0f5054a54b00b300d100714fa9408180
778001010101565e00a0a0a029503020
350029372100001a000000ff00395832
565937314f3137344c0a000000fc0044
454c4c205532353135480a20000000fd
0038561e711e010a20202020202001c0
02031cf14f1005040302071601141f12
132021222309070783010000023a8018
71382d40582c450029372100001e011d
8018711c1620582c250029372100009e
011d007251d01e206e28550029372100
001e8c0ad08a20e02d10103e96002937
21000018483f00ca808030401a501300
29372100001e00000000000000000057
TearFree: auto
supported: off, on, auto
output_csc: bypass
supported: bypass, tvrgb, ycbcr601, ycbcr709
audio: auto
supported: off, on, auto
scaling mode: None
supported: None, Full, Center, Full aspect
dither: off
supported: off, on
underscan vborder: 0
range: (0, 128)
underscan hborder: 0
range: (0, 128)
underscan: off
supported: off, on, auto
coherent: 1
range: (0, 1)
link-status: Good
supported: Good, Bad
CONNECTOR_ID: 54
supported: 54
non-desktop: 0
range: (0, 1)
2560x1440 59.95*+
2048x1152 60.00
1920x1200 59.88
1920x1080 60.00 50.00 59.94 30.00 25.00 24.00 29.97 23.98
1920x1080i 60.00 50.00 59.94
1600x1200 60.00
1680x1050 59.95
1280x1024 75.02 60.02
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
HDMI-0 disconnected (normal left inverted right x axis y axis)
TearFree: auto
supported: off, on, auto
output_csc: bypass
supported: bypass, tvrgb, ycbcr601, ycbcr709
audio: auto
supported: off, on, auto
scaling mode: None
supported: None, Full, Center, Full aspect
dither: off
supported: off, on
underscan vborder: 0
range: (0, 128)
underscan hborder: 0
range: (0, 128)
underscan: off
supported: off, on, auto
coherent: 1
range: (0, 1)
link-status: Good
supported: Good, Bad
CONNECTOR_ID: 56
supported: 56
non-desktop: 0
range: (0, 1)
DVI-0 disconnected (normal left inverted right x axis y axis)
TearFree: auto
supported: off, on, auto
output_csc: bypass
supported: bypass, tvrgb, ycbcr601, ycbcr709
load detection: 1
range: (0, 1)
audio: auto
supported: off, on, auto
scaling mode: None
supported: None, Full, Center, Full aspect
dither: off
supported: off, on
underscan vborder: 0
range: (0, 128)
underscan hborder: 0
range: (0, 128)
underscan: off
supported: off, on, auto
coherent: 1
range: (0, 1)
link-status: Good
supported: Good, Bad
CONNECTOR_ID: 58
supported: 58
non-desktop: 0
range: (0, 1)
/var/log/Xorg.0.log
[ 30439.791] (II) RADEON(0): EDID vendor "DEL", prod id 53358
[ 30439.791] (II) RADEON(0): Using hsync ranges from config file
[ 30439.791] (II) RADEON(0): Using vrefresh ranges from config file
[ 30439.791] (II) RADEON(0): Printing DDC gathered Modelines:
[ 30439.791] (II) RADEON(0): Modeline "2560x1440"x0.0 241.50 2560 2608 2640 2720 1440 1443 1448 1481 +hsync -vsync (88.8 kHz eP)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080"x0.0 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync (67.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080i"x0.0 74.25 1920 2008 2052 2200 1080 1084 1094 1125 interlace +hsync +vsync (33.8 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1280x720"x0.0 74.25 1280 1390 1430 1650 720 725 730 750 +hsync +vsync (45.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "720x480"x0.0 27.00 720 736 798 858 480 489 495 525 -hsync -vsync (31.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "2048x1152"x0.0 162.00 2048 2074 2154 2250 1152 1153 1156 1200 +hsync +vsync (72.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1440x480i"x0.0 27.00 1440 1478 1602 1716 480 488 494 525 interlace -hsync -vsync (15.7 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1440x576i"x0.0 27.00 1440 1464 1590 1728 576 580 586 625 interlace -hsync -vsync (15.6 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "640x480"x0.0 25.18 640 656 752 800 480 490 492 525 -hsync -vsync (31.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080i"x0.0 74.25 1920 2448 2492 2640 1080 1084 1094 1125 interlace +hsync +vsync (28.1 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080"x0.0 148.50 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync (56.2 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "720x576"x0.0 27.00 720 732 796 864 576 581 586 625 -hsync -vsync (31.2 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1280x720"x0.0 74.25 1280 1720 1760 1980 720 725 730 750 +hsync +vsync (37.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080"x0.0 74.25 1920 2558 2602 2750 1080 1084 1089 1125 +hsync +vsync (27.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080"x0.0 74.25 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync (28.1 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1080"x0.0 74.25 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync (33.8 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "800x600"x0.0 40.00 800 840 968 1056 600 601 605 628 +hsync +vsync (37.9 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "640x480"x0.0 31.50 640 656 720 840 480 481 484 500 -hsync -vsync (37.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "720x400"x0.0 28.32 720 738 846 900 400 412 414 449 -hsync +vsync (31.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1280x1024"x0.0 135.00 1280 1296 1440 1688 1024 1025 1028 1066 +hsync +vsync (80.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1024x768"x0.0 78.75 1024 1040 1136 1312 768 769 772 800 +hsync +vsync (60.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1024x768"x0.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "800x600"x0.0 49.50 800 816 896 1056 600 601 604 625 +hsync +vsync (46.9 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1680x1050"x0.0 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync (65.3 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1920x1200"x0.0 193.25 1920 2056 2256 2592 1200 1203 1209 1245 -hsync +vsync (74.6 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1152x864"x0.0 108.00 1152 1216 1344 1600 864 865 868 900 +hsync +vsync (67.5 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1600x1200"x0.0 162.00 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync (75.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1280x1024"x0.0 108.00 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
[ 30439.791] (II) RADEON(0): Modeline "1200x960"x60.0 95.42 1200 1272 1400 1600 960 961 964 994 -hsync +vsync (59.6 kHz e)
Reicht das so?