It's either PSU hardware fault or motherboard hardware/firmware fault. Or both, if one has also damaged the other.
What is making that screeching sound? A jammed PSU fan? Capacitor arcing? Badly oscillating rectifier/regulator diode(s)?
I'm guessing your PSU failed catastrophically. It looks like the most likely cause, except that the PSU hasn't shut itself down, they're (supposed to be) designed to failsafe. It seems to be caught in a loop, for some reason the usual PWR_OK assertion isn't working, the system pulses on and off while something (in the PSU?) screeches in agony.
If you're "lucky" then perhaps the cause is simply one of the modular power cables wiggling loose at one end. Or perhaps the cause is some sort of firmware failure (caused by something as mundane as dead CR2032 battery), a "bricked" motherboard which can be revived.
I'd recommend unplugging the system from AC power immediately. And leaving it unplugged until you can better identify the fault.
A malfunctioning PSU can contain dangerous (even lethal) voltages which can take a long time to discharge. Don't take it apart if you don't have the technical knowledge, and don't use a broken/dangerous PSU as practice to learn on, lol.
A malfunctioning PSU can damage the motherboard (and CPU, GPU, RAM, etc), while a malfunctioning motherboard can damage the PSU (and CPU, GPU, RAM, etc).
I think the PSU is a write-off, but the motherboard/etc might be salvageable. But better to know for sure before wrecking another PSU plugged into the motherboard.
Somebody @ASUS might recognize this as some sort of failure mode specific to their motherboard design.
Post this video on the Corsair forums, too. They might also be able to identify this as a failure mode specific to their PSU design.
(And off-topic, but I really like that beautiful CPU cooler.)
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