Question Whining noises that sound like fluorescent tube coming from my case! please help!

[AverageGamer24]

Hello everyone, Today I casually using my PC when I heard a low-pitch (not high-pitch like coil whine) whining noise coming from my case that sounds like fluorescent tube, I don't really know what's causing it, but it's very annoying and it doesn't seem normal, it happens while PC is idle without any load! The sound happens for like 6 seconds then stops, then happens again after 30 minutes, and so on...
PC specs:
PSU: FSP 500 60APN, CPU: i5 4590, Motherboard: Dell optiplex 7020 motherboard, Memory: 8 GB RAM Dual channel DDR3 1600 MHz, GPU: XFX Raedon RX 570
To give you an idea of how it sounds like, it sounds exactly like this: https://clyp.it/rhcglxzk

 

[ChevetteSCx]

That's easy...it's 60Hz HUM (or 50Hz, depending on global location). This is the frequency at which your AC power system cycles. We'll try a few simple things first :

1.) Ensure both ends of your AC Power Cord are tightly seated into the wall outlet as well as the PSU;
2.) Ensure the AC Power Cord is routed away from ANY OTHER CABLES -or- WIRES at the back of the PC;
3.) If you have a dedicated PC speaker (plugged to the header of the Motherboard, disconnect it);
4.) Ensure that ALL 4 PSU SCREWS are securely fastened -and- the PSU is tight in the case;
5.) Ensure that the side panels of the case are tight and are securely fastened by the screws;
6.) Ensure that ALL of your external 1/8'' jack speaker connections are properly seated into the back jacks;
7.) MOST IMPORTANTLY, ensure that ALL EXTERNAL SPEAKER WIRES are as far from, and do not parallel the AC Power Cord, or any other AC SYSTEM (like a UPS), in any way.

 

[AverageGamer24]

That's easy...it's 60Hz HUM (or 50Hz, depending on global location). This is the frequency at which your AC power system cycles. We'll try a few simple things first :

1.) Ensure both ends of your AC Power Cord are tightly seated into the wall outlet as well as the PSU;
2.) Ensure the AC Power Cord is routed away from ANY OTHER CABLES -or- WIRES at the back of the PC;
3.) If you have a dedicated PC speaker (plugged to the header of the Motherboard, disconnect it);
4.) Ensure that ALL 4 PSU SCREWS are securely fastened -and- the PSU is tight in the case;
5.) Ensure that the side panels of the case are tight and are securely fastened by the screws;
6.) Ensure that ALL of your external 1/8'' jack speaker connections are properly seated into the back jacks;
7.) MOST IMPORTANTLY, ensure that ALL EXTERNAL SPEAKER WIRES are as far from, and do not parallel the AC Power Cord, or any other AC SYSTEM (like a UPS), in any way.

OK I will try to do that, and I also took a 3 photos, one for what's there in the back of my case that shows the PSU cord and the sound cord that's plugged to the motherboard and the messy cables around there, 2 is the powerbox (Sorry I don't remember it's spelling in english) that I got everything plugged to, also took a photo of the power cord that powers the powerbox that's plugged on the wall

here:

https://imgur.com/a/P4ZYl8l

View: https://imgur.com/a/P4ZYl8l

 

[ChevetteSCx]

Upon closer inspection...That PowerBAR...SHOULD NOT BE ON TOP OF YOUR CASE LIKE THAT!!

The magnetic Field generated by =/-3A of current @250VAC cycling an 50/60hz from several outlets on an AC PowerBAR which are notorious for being cheaply constructed and unshielded...NO!!

1.) Place the Power BAR under the table, or;
2.) If you need access to the switch on the Power BAR, zip tie it to the leg of the table.
3.) Route your AC cords down the back and off to the left (as viewed from the front) of the table.
4.) Route all the other cords (VGA, HDMI, 1/8 Audio, ANYTHING NOT AC) to the right of the case along the table.

We'll try these things first.

 

[AverageGamer24]

Upon closer inspection...That PowerBAR...SHOULD NOT BE ON TOP OF YOUR CASE LIKE THAT!!

The magnetic Field generated by =/-3A of current @250VAC cycling an 50/60hz from several outlets on an AC PowerBAR which are notorious for being cheaply constructed and unshielded...NO!!

1.) Place the Power BAR under the table, or;
2.) If you need access to the switch on the Power BAR, zip tie it to the leg of the table.
3.) Route your AC cords down the back and off to the left (as viewed from the front) of the table.
4.) Route all the other cords (VGA, HDMI, 1/8 Audio, ANYTHING NOT AC) to the right of the case along the table.

We'll try these things first.

I just found out what was causing the sound, It was because I forgot to get on of my case's side panel screw all the way in which caused the side panel to be shacking and create that type of sound, thanks for your help...

And is having my powerbar/powerstrip on the top of my case like that dangerous? I have that powerstrip since 2014 and it's been working fine since then.