Question Monitor won't work

[pro2legendary]

So im running a triple monitor setup ( all diffrenet brands) but my main display is an ultrawide BenQ XR3501. it has been running perfectly for a couple of years but lately it won't turn on unless i do this specifically . i would have to disconnect it from the power brick, turn on the pc . wait for the pc to open completely and I log in, THEN i can plug back the monitor into the power brick for it to work . I tried everything but nothing else would work. the monitor doesnt even go to sleep mode if i turn it off. it just shows the orange sleep mode light and then turns off 5 seconds after it . my pc is fairly new im running these specs



1080ti

i7 9700k

16GB of corsair's 2666 mghz ram (not sure about the mghz but its above the 2300)

 

[Ralston18]

PSU: make, model, wattage, age, condition?

Could be that the PSU cannot support the full load requirements imposed when trying to boot and support three monitors via the GPU/motherboard.

May have worked for awhile (" a couple of years") but doing so may have brought the PSU to a premature EOL (End of Life)

Swap the monitors around to determine if one of the other monitors ( as "main") will turn on at boot up.

 

[pro2legendary]

The psu is a corsair 750watt, had it for 5+years about now, i swapped the monitors and they work fine and turn on at bootup with the computer but I don’t get why you asked about the pc’s psu? Shouldnt the monitor be on a seperate unit of power for it to work and non dependent on the pc’s psu? Also i tried to only use 2 monitors and the problem still presistes with the benq xr3501. It works perfectly fine once it works but the issue of it is the booting up process of the monitor