My Nitro 5 had the same issue. Bought a powerful laptop cooling fan, but noise was just as bad. Bought a small bottle of Compu-Lube lightweight lubricant. Added 3 drops to moving fan, but not much better. Then I got lucky. I removed the four teeny-tiny screws that hold the fan cover tightly against the moving part of the fan (photo provided). This did not make the cover fall off, because the routing tape that brings cool air in through the vents holds it down just fine. Removing those 4 screws did the trick, fans are whisper quiet now. I still hear them, but no more buzzsaw noise.