I tested it extensively on my Q90r, because I really wanted 4k@120hz as well. The result is, the Q90r can do 4k@120hz with YCbCr 420 (as described in the manual), but without HDR! HDR can either not be turned on (for example in Windows 10), is ignored by the program or image and color errors occur with HDR enabled at 4k@120hz. The only thing that works without problems is 1440p@120hz and activated HDR (with RGB and YCbCr).
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