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I want to be able to forcibly set my raspberry pi hdmi video output to a non-standard (non-DMT/CEA) refresh rate. I am not concerned with whether my monitor can handle the video (this is partially the point).

Are there standard applications for the raspberry pi which can help me accomplish this? So far all I've been able to find is setting via the config file to the standard values as shown here.

Any help you can give is appreciated!

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  • Have you tried this? If it works out, feel free to add your own answer (you may have to wait 24 hours or something first). Found that link in the official docs.
    – goldilocks ♦
    Oct 6, 2015 at 19:32
  • @goldilocks worked for me... I just used that to FINALLY get my monitor with the funny refresh rate to work. Cheers!
    – Kachamenus
    Oct 7, 2015 at 1:01

1 Answer 1

Reset to default
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Thanks to @goldilocks for this excellent link.

To summarize the process I used:

sudo nano /boot/config.txt

Inside the file, uncomment (if necessary) and change the lines:

hdmi_group=2
hdmi_mode=87

This will tell the pi to load on startup the custom CVT settings which are automatically defined as mode 87. Beneath those lines, fill in the following line:

hdmi_cvt=<width> <height> <framerate> <aspect> <margins> <interlace> <rb>

ie:

hdmi_cvt=1680 960 70 3 0 0 0

ctrl+x, Y+enter

To reload the new CVT at port 87 from the config file, you will need to do a reboot:

sudo reboot

To make sure that your settings have been applied after reboot:

tvservice -s

Note that the pixel clock on the pi has limits, and if it cannot handle the requested setting it will revert to the default 1440x900 @ 60Hz

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