PSU Seasonic beats

[karpusan]

Hello, I built a computer, everything is OK, temperatures are within limits, bur PSU Seasonic S12II-520W audibly "beats" (frequency cca 2x per sec. Where is the problem?

 

[Ubrales]

2nd. harmonic frequency. Contact Seasonic tech support. They may have a solution, or they will tell you to RMA it.