Weird noise from PSU

Recently I have started to notice this weird noise which I believe Is coming from the PSU, I don't really no how to describe the sound but basically it's like the sound is slightly amplified but is inconsistent in the noise it makes, making it rather annoying. The issue can be resolved by slightly tilting my case, about 1 cm of movement and the noise disappears, any ideas what this could be?

Something on a fan blade weighing it down and causing it to oscillate?