Metal noise dissipating CPU

[sergip10]

Hello, about a month ago I built a PC and everything was working correctly until 4 days ago, when the CPU cooler started making a strange and annoying noise. The noise only occurs when I push the CPU, but it only occurs at intervals and it has me worried.

I have checked that there are no rubs with cables or anything like that and everything is in order, so I don't know where it could be coming from. I tightened 2 of the screws that anchor the cooler, since I can't reach the other 2 with the screwdriver.

For more information, the processor is a Core i5 4570 and the cooler is a Cooler Master Hyper 212 Evo.

Thank you!

[whoololon]

Check that you mounted the rubber pads between the heatsink and the fan.