I put together a new PC two weeks ago using some parts from my existing PC.
My new parts: 3900x, x570 meg ace, 2080 ti, 32gb 3600mhz g.skills ripjaws, cpu cooler, 1tb m2 nvme drive, PG27UQ (display port)
old parts: cd-rom drive, 120gb old sata ssd (windows install drive), 1tb sata HDD, corsair hx850i
seems to have started when I enabled XMP and set the memory speed to 3600mhz in bios.
today it took me like 7 tries hitting the power button off and on to get it to post. When it DOES post, it'll work flawlessly for hours until I turn it off.
All the components seem to be getting power, everything lights up and all the fans spin, my monitor just doesn't get any signal and stays off. But when it does turn on, the monitor picks it up and displays normally.