newly created mode using xrandr on 1440x900_60.00 has no effect on my ubuntu 15.10

Question

I'm on ubuntu 15.0 with gnome 3.16.4 installed

everything is fine except the screen resolution. my HP LCD tells me that it supports the max resolution of 1440x900. however there's no such mode in the display setting. so I tried to manually create one by issuing the following commands:

gtf 1440 900 60
# 1440x900 @ 60.00 Hz (GTF) hsync: 55.92 kHz; pclk: 106.47 MHz Modeline "1440x900_60.00"  106.47  1440 1520 1672 1904  900 901 904 932  -HSync +Vsync
xrandr --newmode "1440x900_60.00"  106.47  1440 1520 1672 1904  900 901 904 932  -HSync +Vsync
xrandr --addmode VGA1 "1440x900_60.00"
xrandr -s 1440x900

there I see no errors, my display flickers for a while and nothing. my resolution is back to the default 1024x768 . so what gives? any help will be appreciated.

Answer 1

ok so after going through the guts of ubuntu aka xorg.log.0, it turned out something was messed up with my VGA cable (i know it's ancient) but anyway, I changed the VGA cable and viola! got my resolution automatically as well as the rest of them that I get on my windows. so if you are having similar problem, please save yourself a few days of torture and change your VGA cable.