Eu tenho o mesmo monitor conectado via cabo DVI-para-HDMI:
Section "Monitor"
Identifier "DELL S2240L"
ModelName "DELL S2240L"
VendorName "DEL"
# Monitor Manufactured week 32 of 2014
# EDID version 1.3
# Digital Display
DisplaySize 480 270
Gamma 2.20
Option "DPMS" "true"
Horizsync 30-83
VertRefresh 56-76
# Maximum pixel clock is 170MHz
#Not giving standard mode: 1152x864, 75Hz
#Not giving standard mode: 1280x1024, 60Hz
#Not giving standard mode: 1920x1080, 60Hz
#Extension block found. Parsing...
Modeline "Mode 13" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
Modeline "Mode 0" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
Modeline "Mode 1" 148.500 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
Modeline "Mode 2" 74.250 1920 2008 2052 2200 1080 1082 1087 1125 +hsync +vsync interlace
Modeline "Mode 3" 74.250 1280 1390 1420 1650 720 725 730 750 +hsync +vsync
Modeline "Mode 4" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
Modeline "Mode 5" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
Modeline "Mode 6" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
Modeline "Mode 7" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
Modeline "Mode 8" 25.200 640 656 752 800 480 490 492 525 -hsync -vsync
Modeline "Mode 9" 74.250 1920 2448 2492 2640 1080 1082 1089 1125 +hsync +vsync interlace
Modeline "Mode 10" 148.500 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync
Modeline "Mode 11" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
Modeline "Mode 12" 74.250 1280 1720 1760 1980 720 725 730 750 +hsync +vsync
Modeline "Mode 14" 74.25 1920 2008 2052 2200 540 542 547 562 +hsync +vsync interlace
Modeline "Mode 15" 74.25 1280 1390 1430 1650 720 725 730 750 +hsync +vsync
Modeline "Mode 16" 27.00 720 736 798 858 480 489 495 525 -hsync -vsync
Option "PreferredMode" "Mode 13"
EndSection
Você pode baixar o arquivo EDID aqui .