My PSU whines between 8AM and 8PM and doesn't whine at all during the weekends, first i thought my PSU had a failing cap but when i opened it up all capacitors look fine to me (no leaking or bulging) voltage is also within tolerence.

What strikes me as weird is that it stops whining as soon as my electricity meter switches from day time to night-time electricity usage. I'm not very savvy when it comes to electricity, but could this be bad? The upstairs wiring in my house is pretty shit to begin with.

I don't really have to funds to get an electrician to look at the wiring, i could bother the land lord about it though.

Edit; I have a BQ 450w PSU powering an ATI APU build