[email protected]:~# lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 82852/855GM Integrated Graphics Device (rev 02)

[email protected]:~# xrandr
 SZ:    Pixels          Physical       Refresh
*0   1024 x 768    ( 347mm x 260mm )  *60  
 1    640 x 480    ( 347mm x 260mm )   60  
 2    800 x 600    ( 347mm x 260mm )   60  
Current rotation - normal
Current reflection - none
Rotations possible - normal left inverted right 
Reflections possible - none

915resolution is a tool to modify the video BIOS of the 800 and 900 series
Intel graphics chipsets. This includes the 845G, 855G, and 865G chipsets, as
well as 915G, 915GM, and 945G chipsets. This modification is necessary to
allow the display of certain graphics resolutions for an Xorg or XFree86
graphics server

 apt-get install 915resolution

[email protected]:~# 915resolution -l
Intel 800/900 Series VBIOS Hack : version 0.5.2

Chipset: 855GM
BIOS: TYPE 1
Mode Table Offset: $C0000 + $29f
Mode Table Entries: 39

Mode 30 : 640x480, 8 bits/pixel
Mode 32 : 800x600, 8 bits/pixel
Mode 34 : 1024x768, 8 bits/pixel
Mode 38 : 1280x1024, 8 bits/pixel
Mode 3a : 1600x1200, 8 bits/pixel
Mode 3c : 1920x1440, 8 bits/pixel
Mode 41 : 640x480, 16 bits/pixel
Mode 43 : 800x600, 16 bits/pixel
Mode 45 : 1024x768, 16 bits/pixel
Mode 49 : 1280x1024, 16 bits/pixel
Mode 4b : 1600x1200, 16 bits/pixel
Mode 4d : 1920x1440, 16 bits/pixel
Mode 50 : 640x480, 32 bits/pixel
Mode 52 : 800x600, 32 bits/pixel
Mode 54 : 1024x768, 32 bits/pixel
Mode 58 : 1280x1024, 32 bits/pixel
Mode 5a : 1600x1200, 32 bits/pixel
Mode 5c : 1920x1440, 32 bits/pixel
Mode 7c : 1280x801, 8 bits/pixel
Mode 7d : 1280x801, 16 bits/pixel
Mode 7e : 1280x801, 32 bits/pixel

[email protected]:~# 915resolution 7e 1280 801 32
Intel 800/900 Series VBIOS Hack : version 0.5.2

Chipset: 855GM
BIOS: TYPE 1
Mode Table Offset: $C0000 + $29f
Mode Table Entries: 39

Patch mode 7e to resolution 1280x801 complete