Question Case fan keeps wavering

[Jacob 51]

My case fan keeps slowing down and speeding up, while the RPM still remains low and I can't hear anything, its not a constant RPM. You can notice it running slow and then fastening up in 3 seconds, its like a cycle.
The fan is connected directly to the PSU (it doesn't have 3 pin headers, only molex cable). The fan came preinstalled in my ANT Esports ICE 130 AG cabinet. I checked the cables and they seem to be fine.

 

[lvt]

A good case fan with direct connection should run at its highest designed speed.

Your fan might have a problem with bearing or internal circuit.

 

[Jacob 51]

A good case fan with direct connection should run at its highest designed speed.

Your fan might have a problem with bearing or internal circuit.

That was unexpected, since I just got the case.
It may be a faulty fan that they gave me

 

[lvt]

That was unexpected, since I just got the case.
It may be a faulty fan that they gave me

You can test the fan on other Molex, if it acts the same, it's faulty.