Page 142 of the
EVGA X299 DARK User Guide.
POST beeps are used in conjunction with the POST Code indicator to help determine the root cause when your system fails to boot. However, modern UEFI/BIOS motherboards also use the speaker to convey helpful information, such as USB device detection. As a result, users may become confused about the number of beeps emitted, making the POST code beep - while still helpful - not as useful as it once was. Many motherboards will beep 1-2 times per USB device plugged in at boot; some will beep more based on functions of the device. These detection beeps may occur at the same time as the system’s POST beeps, sometimes making it a challenge to separate the POST beeps from the USB initialization. Since the POST code indicator now fills most of the role previously held by audible beeps, there are far fewer POST beeps to help debug problems, compared to previous motherboard generations. You can disconnect USB devices to confirm that's what's causing all the incessant beeping.
Turn off Speaker Beep in the
Boot section of the BIOS before it drives you bonkers, or even more bonkers.
Pick a
GPU Support Bracket you like or make something up yourself.