I'm using the HP ProDesk 400 G6 MT with an LG BK750Y dual screen setup. One screen is connected to the HDMI port, and the other screen is connected to the displayport. Infrequently after power-up, the screen connected to the displayport is not getting any output from the displayport. The screen just outputs the message "Checking signal", and then it goes into standby. Rebooting does not help, but simply entering the BIOS and leaving it makes the dispaylport working for some boot cycles. A CMOS reset or reset to factory defaults also resolves the problem, but after some boot cycles, the problem turns up again. I have updated the BIOS to the most recent version, and I have performed a CMOS clear. The HP support sent an onsite technician, but he refused to change the mainboard since the problem was not reproducible to him (it happens sporadically). I'm looking forward to any helpful suggestions.
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