so it only started happening about a week ago and every time i turn on my computer at this point it does it. i know its from my psu because when it does it i can actually feel the vibration of my psu and its like a phone on a constant vibrate. it sounds like a lawn mower. its louder than you might think. im not sure if its the fan cuz im not sure how a fan could get THAT loud. but to get it to stop i have to punch it over and over and quite frankly, my knuckles are getting sore lol.
Most likely the fan in the PSU is failing. You can replace it very easily.
Once a fan dies it will get as loud as heck.
Because it works after you hit it is has to be mechanical.
If I was coil wine ETC a hit would not fix it.
Just replace the fan and you will be good.
If the PSU still has a warranty use it, If not just open the PSU and replace the fan.