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I've seen the older thread asking about a pi 2 on a cinema display, but the responses weren't helpful.

I have an old Apple Cinema display that does work - had an ancient mac up and running, but that machine is too old to do what I need. I have a Pi4 running Raspberry Pi OS(32bit). Using another monitor on HDMI-0 to set things up, I'm trying to change settings on HDMI-1 that will work on the Cinema Display.

Regardless of the settings (that I've found), the light on the cinema display outputs three short blips indicating that the video received is the wrong format. Can anyone shed light on this issue or should I put the Cinema Display back in storage for some other future use?

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  • the resolution you need is 2560 x 1440 ... what settings have you tried? you'll probably need to use hdmi_group=2 and hdmi_mode=87 to use user defined settings, and then figure out the value for hdmi_timings= or perhaps hdmi_cvt=2560 1440 60 3 0 0 0 Apr 20 at 23:51
  • Resolution depends on the monitor age - it may be as low as 1600×1024 but hard to guess as OP does not state native resolution. It could be 1920 × 1200 1680 × 1050 or 2560 × 1600 also...
    – user130616
    Apr 21 at 1:56
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I am having the same issue, although I am running Debian Buster (64) on a Pi4. I am accessing via VNC on a 27" iMac (2560x1440). So what I have to do is:

  1. $ cvt 2560 1440 60 This generates the mode line for the command below (only necessary once)
  2. After reboot I have to run this:

$ sudo xrandr --newmode "2560x1440_60.00" 312.25 2560 2752 3024 3488 1440 1443 1448 1493 -hsync +vsync

$ sudo xrandr --addmode HDMI-1 2560x1440_60.00

$ sudo xrandr --output HDMI-1 --mode 2560x1440_60.00

I have not found a way to make this stick on reboot. Any kind of automatic start-up execution I use (Cronjob, rc.local) always generates an error like "Can't open display"

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  • perhaps you need to make it part of the X11 startup when DISPLAY would be available Apr 22 at 0:21

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