this is not universally true. i bought a new 1000W seasonic prime ultra titanium for use in a hashcat rig not too long ago, and the PSU would immediately switch off when all the cards drew power to 100% (all the cards drew no more than 800W or so at load.) there is a newegg reviewer that experienced similar issues in a system with dual RTX cards. ended up buying an EVGA supply instead and that has been solid, even at 24x7 operation.