The curious case of my power supplies

A while ago I was posting because I have had 2 evga supernova power supplies that made a tick noise.

First was Bronze rated one, started ticking 9 months after I first built it

I swapped it with a platinum supply, same wattage, brand, and it was fine for 3 days before ticking again

I just ignored it as no one here knew what it was.

It went away again, for 5 days havent heard it once, it happens every 30 seconds and not one tick was emitted.

Strange.
 


I actually found out the problem. My PSU's had been directly in the wall outlet, bad idea, but anytime someone turned on a vacuum cleaner in my home then the ticking arrived. Power fluctuations did it!

I just yesterday went to best buy and bought a somewhat decent 40 dollar surge protector for an added line of defense.