Is the high weight of Noctua coolers dangerous for the CPU, motherboard or socket?

No. Noctua coolers possess an extremely reliable SecuFirm™ mounting system. Thanks to the screw connection with the backplate on the rear side of the motherboard, the exceedance of the weight recommendations by Intel and AMD common among high-end coolers is completely unobjectionable.

SecuFirm2™ mounting systems use high-grade coil springs to achieve perfect contact pressure. No guesswork regarding how far to tighten the mounting screws, no risk of damaging the socket or motherboard with excessive pressure!