Re: Constant BEEEEEEE... sound from motherboard?
The RED plug on that PSU is for PCI-E (i.e. a dedicated GPU) so that is not a concern.
You need to determine the source of the problematic sounds. On the bench would be the best possible means to determine the source. You could leave the CPU & Heatsink mounted to the Mobo but remove everything from the case.
Remove EVERYTHING from the case
Leaving the CPU/heatsink mounted to the Mobo,
Install 1 stick of RAM.
Install the video card and attach the power supply connection(s) to the card if your card needs it.
Connect the monitor to the video card.
Connect the power supply to the motherboard with both the 24pin main ATX Power connection and the separate 4 or 8 pin power connection.
Connect power to the power supply.
Do NOT connect ANYTHING else. Make sure you have the power connector on the CPU fan connected.
Use a small screwdriver to momentarily short the power switch connector on the motherboard. Consult your motherboard manual to find which two pins connect to your case's power switch. Then touch both pins with a screwdriver to complete the circuit and boot the system.
If all is well, it should power up and you should get a display. Then assemble the parts into the case and try again. If the system now fails to boot, you have a short in the case and need to recheck your motherboard standoffs.
If the system does not boot after this process, then you most likely have a faulty component. You'll need to swap parts, start with the power supply, until you determine what is defective.