Here is some infomation you may need for your dell display.
[VERSION]
1.0;
[MONITOR_DESCRIPTION]
Date = 2004/3/29;
FileRevision = "1.0";
Manufacturer = "Dell";
ModelNumber = "WUXGA 1920x1200 @ 60Hz";
MonitorType = COLOR;
[OPERATIONAL_LIMITS]
MaxHorPixel = 1920; // pixels
MaxVerPixel = 1200; // lines
VideoType = ANALOG;
SyncType = TTL;
SyncConfiguration = SEPARATE;
MaxPixelClock = 200.000; // MHz
MinHorFrequency = 31.500; // kHz
MaxHorFrequency = 110.000; // kHz
MinVerFrequency = 50.000; // Hz
MaxVerFrequency = 90.000; // Hz
[ESTABLISHED_TIMINGS]
"1920x1200 @ 60Hz"
---
Section "Monitor"
HorizSync 31.5 - 94
VertRefresh 50 - 90
# 1280x800 @ 60.00 Hz (GTF) hsync: 49.68 kHz; pclk: 83.46 MHz
ModeLine "1280x800" 83.5 1280 1344 1480 1680 800 801 804 828
# 1280x800 @ 75.00 Hz (GTF) hsync: 62.62 kHz; pclk: 107.21 MHz
Modeline "1280x800" 107.21 1280 1360 1496 1712 800 801 804 835
# 1280x800 @ 85.00 Hz (GTF) hsync: 71.40 kHz; pclk: 123.38 MHz
Modeline "1280x800" 123.38 1280 1368 1504 1728 800 801 804 840
# 1280x800 @ 100.00 Hz (GTF) hsync: 84.80 kHz; pclk: 147.89 MHz
Modeline "1280x800" 147.89 1280 1376 1512 1744 800 801 804 848
# 1680x1050 @ 60.00 Hz (GTF) hsync: 65.22 kHz; pclk: 147.14 MHz
Modeline "1680x1050" 147.14 1680 1784 1968 2256 1050 1051 1054 1087
# 1680x1050 @ 75.00 Hz (GTF) hsync: 82.20 kHz; pclk: 188.07 MHz
Modeline "1680x1050" 188.07 1680 1800 1984 2288 1050 1051 1054 1096
# 1680x1050 @ 85.00 Hz (GTF) hsync: 93.76 kHz; pclk: 214.51 MHz
Modeline "1680x1050" 214.51 1680 1800 1984 2288 1050 1051 1054 1103
# 1680x1050 @ 100.00 Hz (GTF) hsync: 111.20 kHz; pclk: 256.20 MHz
Modeline "1680x1050" 256.20 1680 1808 1992 2304 1050 1051 1054 1112
# 1920x1200 @ 60.00 Hz (GTF) hsync: 74.52 kHz; pclk: 193.16 MHz
Modeline "1920x1200" 193.2 1920 2048 2256 2592 1200 1201 1204 1242
# 1920x1200 @ 75.00 Hz (GTF) hsync: 93.97 kHz; pclk: 246.59 MHz
Modeline "1920x1200" 246.59 1920 2064 2272 2624 1200 1201 1204 1253
# 1920x1200 @ 85.00 Hz (GTF) hsync: 107.10 kHz; pclk: 282.74 MHz
Modeline "1920x1200" 282.74 1920 2072 2280 2640 1200 1201 1204 1260
# 1920x1200 @ 100.00 Hz (GTF) hsync: 127.10 kHz; pclk: 337.58 MHz
Modeline "1920x1200" 337.58 1920 2072 2288 2656 1200 1201 1204 1271
Option "DPMS"
EndSection
---
I got this information from this link:
http://www.bolthole.com/solaris/DELLwxga.pkg
You might want to delete the lines above 60hz refresh.