I have three Dell U2715H monitors running off single DP cable out of Nvidia 1650 card. I never used to have any issues but recently they started not waking up. I can power the monitors off, reboot and still wont wake up. The only fix I have found is getting PC started and unplugging DP cable for about 5 to 10 seconds. Sometimes it takes twice.  I have reformatted the PC recently (no help) and just tried a MSI RTX 3060 card. Same issue. It's quite annoying and I don't think I could get into BIOS if I needed to as I never see that anymore.