Question Intermittent 1xlong, 3xshort beeps, and white LED on PRIME Z490-A

Hello, Everyone!

I'm having an issue with my new motherboard (ASUS PRIME Z490-A) I just purchased last month from TechINN, the only e-tailer which still sold it online at the time of purchase (12-15-2021).

The Issue: Sometimes the computer beeps once indicating a successful POST. Then seconds later I hear 1xlong + 3xshort beeps and the white LED on the motherboard near the RAM lights up. This has happened with and without a dGPU installed. Though it is intermittent, and sometimes the beeps don't occur, and I can access the BIOS (only from the iGPU. I NEVER could access the BIOS from the dGPU). Despite the beeps, the computer sometimes continues booting and the monitor first comes on when the PC reaches the Windows 11 log-in screen. So it seems as though the Windows 11 OS sees the dGPU (EVGA GTX 750 Ti, 2GB GDDR5) fine, but the BIOS does not recognize it at all (i.e., no image until the OS boots up). At first, I thought this must be because my GPU is just way too old, but I experienced the series of beeps also when no dGPU was even installed and the monitor was driven entirely off my Core i9 10900K CPU! So if anyone can tell me if it's an incorrect BIOS setting, or do I just need to send my motherboard back to ASUS for repair or replacement (if, it is still even under warranty). Thank you all kindly for your help in advance.

In BIOS (with dGPU Installed, but DisplayPort cable from my monitor plugged into iGPU DisplayPort), here are my settings:

Primary Display: Auto
DVMT Pre-Allocated: 64M
RC6(Render Standby): Enabled
PCIEx16_1 Link Speed: Auto
PCIEx16_2 Link Speed: Auto