I recently purchased an Acer AL1916W, a nice Widescreen TFT with an unusual resolution of 1440×900 px, which was at first a challenge to configure. I tried various setups in xorg.conf, en- and disabled DDC, even wrote my own modelines. The best I got was an 1440×900 resolution with black broders (~ 3 cm) on the left and right.
Until i read the manual (RTFM!), which I couldn’t find at the Acer Worldwide Homepage, so i provide it here: Acer AL1916W Handbook. At the end of the manual the reference signalmodes are listed:
Display Mode: WXGA 1440×900
Horizontal Frequency (kHz): 55.935
Vertical Frequency (Hz): 55.887
Pixel Frequency (MHz): 106.5
SYNC Polarity (H/V): -/+
At first i was puzzeld, because the refreshrate isn’t an integer (as I thought it should be). Nevertheless I used gtf, a small xorg-tool to calculate VESA Modlines, with this values:
~ # gtf 1440 900 55.887
# 1440x900 @ 55.89 Hz (GTF) hsync: 51.97 kHz; pclk: 98.96 MHz
Modeline "1440x900_55.89" 98.96 1440 1520 1672 1904 900 901 904 930 -HSync +Vsync
Using this ModeLine in xorg.conf, the Acer detects a 60 Hz refresh rate, and the auto-adjust works fine, the borders are gone.