After owning Yoga 720 for about a year and half, my daughter's machine finally start making the crazy flapping noise. Most of the solution that I found online was basically tricking the machine not to activate the fan. With that said, I decided to open up the machine and found one of two black strip of tape going across mesh that appeared to be stretched. This strip of tape is directly over the fan (there are two fans) when the metal plate is covered. After some testing, I found that was the reason for the noise. So, I carefully pull the stretched tape and retape across the same location so that it is tightly over the mesh. I think this is some sort design defect where tape get stretched over period of time. Anyway, the solution is simple, but does require a T-5 Torq tool to open the back plate followed by re-tap to avoid flapping noise. Hopefully this helps.