Trying to pinpoint the problem with my gaming pc

Ever since i bought my pc it has been underperforming massively and it’s extremely frustrating and im trying to figure out what might be causing it. I have a RX 580 sapphire, i7 2600k cpu @ 3.40ghz, 16gb ram, 500w psu and a standard intel motherboard. This pc can’t even run fortnite and i wish i was joking, i think i have pinpointed the problem but i might be wrong. Basically even when my computer is sat on the desktop there’s always a loud buzzing coming from inside the psu, i’m not sure if this is normal for a psu to be loud and screeching like this and it gets way worse when i attempt to run a game, even moving my mouse curser round the homescreen makes it buzz. At first i thought the reason for it underperforming might be the heat so i added a few extra fans and my temps are sat at a good number and still the issue stayed. A typical example of when im running a game is the screen would go black but not fully turn off and i’ll hear a buzz projected into my headphones until i have to completely shut the pc off. I’d appreciate any help or opinions thank you.