This is my first experience with a Coolermaster PSU and i cannot say i am satisfied. I purchased a G750M PSU a month ago from an online-retail shop here in Cyprus. The PSU is mounted on a Corsair Graphite 780T. My issue is that i hear a constant whistling noise from the PSU. I cannot distinguish if it is coming from the fan or the internal components. The sound is extremely irritating and definitely noticable in my enviroment, especially on quiet hours. I concluded it is the PSU after i spend two days and nights taking my PC apart, deactivating all other fans, tighten and loosen every screw i could find in and out of my PC, and performing various acoustic tests. I returned it on the shop and they said they will test it to confirm the sound. Their tests returned nothing! I even looked myself at their test PC and i couldn't hear the sound it was producing when it was installed on my PC at home and of course they refused to replace it. I beg for anyone's help because this PSU is part of my new PC, which i saved money for an entire year in order to buy it. I know that i bought it a month ago and it is of course under warranty so what can i do here? What could be causing the issue on my PSU? I am one step before i ram my head to the wall from the desperate position i am in. I would gladly apreciate anyone's advice on the matter. Thank you and i apologize for the long post.