Not interested in using HDMI considering that the specs for the AW2721D do not support 240Hz over HDMI. QHD 2560 x 1440 (DisplayPort: 240 Hz, HDMI: 144 Hz) If DisplayPort isn't functioning properly, then this monitor must be defective.   People have been experiencing this due to firmware updates to current gen GPUs to support reBAR, which is impacting DSC.  The workaround is to use hdmi to enter BIOs, or downflash the vBIOs if the issue is the display stream compression issue that a lot of other people are experiencing, or deal with it until it gets patched.   If that is the issue (not saying it is, there could be other issues) but if so, it's not the monitor, it's the GPU firmware.  You could find out if that is likely the issue by checking to see if hdmi works for BIOS POST screens.  Other than that, dp should work fine, hdmi would only be to access BIOS settings which seemed like what you wanted to do. 
I just picked up the AW2721D monitor. Happy with it so far, but just ran into a major issue. At first I thought the monitor was just slow to wake up as every time I booted up my system, it would only wake up once the Windows 10 logon screen was showing. But when I used the SHIFT-RESTART shortcut to boot directly into UEFI BIOS, I realized that instead the monitor simply will not display the POST or BIOS screens at all. It just goes into standby mode and won't wake up. I'm using a known good DisplayPort cable that was previous working on another Dell 1440p 144Hz monitor without issues. Is this just a bad monitor that I need to send back? Or any other thoughts on this? It's connected to an EVGA 3080 TI FTW3 GPU with fully updated firmware. Motherboard is also running the latest BIOS. Although at this point, I can't get to the BIOS to check anything now because the monitor simply goes to sleep.
AW2721D, DP, does not display BIOS or POST screen