I am trying to get a custom resolution to run on my 4k, 60Hz TV. I am mostly working on a Thinkpad that only supports 4k@30Hz via Display Port. I would much rather work on a lower resolution with a higher refresh rate, so I set out to generate a custom modeline (1440p @60Hz). This is necessary since the TVs edid information only forwards 4k and 1080p resolutions.

The first tool I was using is cvt:

> cvt 2560 1440 60
# 2560x1440 59.96 Hz (CVT 3.69M9) hsync: 89.52 kHz; pclk: 312.25 MHz
Modeline "2560x1440_60.00"  312.25  2560 2752 3024 3488  1440 1443 1448 1493 -hsync +vsync

I added the mode to xrandr and started the output to my TV. The following artefact is appearing now: Replicated left side of monitor

The left side of everything on my monitor gets replicated on the right side and overlaps a significant part of the right side of the monitor. This overlap is clearly only happening on the monitor level since I can move my mouse "below" the overlap on the right side.

What I did next was trying to understand this webpage about modeline calculation: Modeline Details.

I used the Modelines in my TVs edid and based on that information recalculated the clocks etc. for my specific resolution and my TV. However, it does not work. I cannot move the overlap an inch to the right or left regardless of the value I change in the given Modeline (except of course by changing the resolution itself). I need to be pointed into the right direction to understand where this artefact is coming from and how to resolve it.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.