I had the same issue after installing RTX 3090 FE card, and discovered the issue was due to having a USB charging device plugged into my rear IO USB port.
Vary strange, as I have had the USB charging device while running RTX 2080TI card with no issues, after swapping out card to 30-series card I was getting the 4-beeps at start-up,.. after unplugging the USB device and restarting the beeps have not happened, I confirmed by plugging the USB charger back in and re-start PC and sure enough the 4-beeps are back.
So perhaps check all your USB devices one at a time, re-start PC, see if that solves your issue.
Was not a big deal unplugging the charging device, was an easy fix.
Good luck.