Question I think there's something wrong with my PSU. Pulsing sound when plugged in and no system response ?

May 19, 2022

This is my first time in these forums. Today, I'm here because I'm having issues with my PC that I believe are PSU related.

Around 3 weeks ago, my PC started to power cycle on press of the power button. For about 24 hours I was unable to get any signs of life other than a faint pulsing noise from the PSU. When the power switch is off, the pulsing will slowly transition into normal coil whine in which all system lights would light up. (My motherboard has an onboard RGB logo and lit up audio I/O ports)

With enough flipping the switch on and off, eventually the PC would start to work again. It would turn on as normal if I flipped the switch and let it sit for 4-5 minutes. However, recently I would have to redo the process every time I shut it down. I do not want to have to leave my PC on but I also don't want to have to spend up to an hour each time I want to use it. Tonight I haven't even been able to turn it on period!

I've noticed that when unhooked from the ATX motherboard connector, the pulsing stops.

Some specs for reference:
Intel Core i9-10850k
NZXT Kraken M22 cooler
32gb (16x2) Corsair Vengeance LPX DDR4-3000 memory
Asus ROG Strix Z490i Mini-ITX motherboard
Seagate 2tb SSHD 7200RPM
Sandisk 1tb SSD (boot drive)
MSI Titanium GTX 1070 ti
Gigabyte GP750W power supply (80+ Gold)

I have considered that the problem may be related to the CMOS battery, yet the PC was built last January. I figured that they don't die that quickly, as my previous build's CMOS never died (after 7+ years of use).

I also have not tried the paperclip test, but I can confirm that the PC has turned on with enough fiddling. (If I use a paperclip, will I get electrocuted? I'm also worried about that)

This is the sound my PSU is making

Any advice is appreciated. Thanks in advance.