U2723QE, black screen when switching inputs, #3

I have the same model and almost the same problem. Booting the PC ALWAYS results in the black screen and unresponsiveness to buttons. BIOS output is visible before, then nothing. Power LED remains on, backlight seems to be on, too. Connected via DP to a Nvidia Quadro. I even had this issue once when selecting the diagnostic mode in the bios of the (Dell-) PC, so no windows involved. A hard power cycle for U2723QE is necessary to resolve.