I recently put together a gaming pc using a corsair 200R case, and with the pc I also bought a 4 pack of coolermaster 120mm fans. I neglected to put in the 2 side intake fans until I got the graphics card, which came a day ago. I also powered both side fans using a rosewill pwm splitter (http://www.newegg.com/Product/Product.aspx?Item=N82E16812119248&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-NA-_-NA&gclid=CJDEqc7a0bQCFQq0nQodGhMARQ) because my motherboard only has 5 fan slots (2 cpu, 2 chassis, 1 power fan[?]). After putting in the side fans, I realized that one of them was making a humming noise, and if I took the fan off the side panel, or if I covered the intake grate for the fan then the noise ceased. After rewiring a little with the pwm splitter, the other side intake fan began making the same noise.
Note that I did not plug the female 4 pin connector of the splitter into the motherboard, though i may be forced to try that.
I'll try any possible solutions, and thanks in advance.