Dell Precision 3560 with T500 30Hz max on external display via HDMI

For some reason my new Dell laptop refuses to work above 30Hz with my monitor at 4K.

This same monitor and cable work just fine over HDMI connected to my Windows box. I haven’t tested this same laptop using Windows since I installed Linux as soon as I got it, but I suspect it’ll work.

60Hz and 75Hz modes are listed, but when I try to use them the screen just goes black without turning off.
nvidia-bug-report.log.gz (1.7 MB)

I also tried 465.31 and replaced HDMI cable with an 8K compatible cable with same results. Any attempt to switch resolution to 3440x1440 at anything above 30Hz results in black screen on the external monitor.

I tested another 4k display and it is working at 60Hz without any issues. Does anyone have any ideas for how to define the exact configuration my display needs to work correctly? Any way to retrieve it from Windows since everything is working correctly there?

I ended up trying a bunch of different refresh rates after seeing this suggested in a SO post and eventually figured out that 59Hz is the highest this monitor will accept. Just in case this helps someone since this post has zero replies.
Try to slowly increase the freq number at the end until you get an error when applying:

cvt 3440 1400 59
# 3440x1400 58.93 Hz (CVT) hsync: 85.51 kHz; pclk: 399.50 MHz
Modeline "3440x1400_59.00"  399.50  3440 3688 4056 4672  1400 1403 1413 1451 -hsync +vsync

Use the output of above command to generate and add new mode:

xrandr --newmode  "3440x1400_59.00"  399.50  3440 3688 4056 4672  1400 1403 1413 1451 -hsync +vsync
xrandr --addmode HDMI-1-1 3440x1400_59.00

And apply:

xrandr --output HDMI-1-1 --mode 3440x1400_59.00