JaYp146
Highly probably that the fans have no capacitors inside, unfortunately it is quite common. Without capacitors fans work but sound much worse.

As for SlipStreams there are many complaints about them in terms of life time. The cause is very simple, they have very poor lubricant inside and very small quantity at that, which totally evaporates within a few months. I would highly recommend to lubricate them just after purchase. Car motor oil i...