It may not be able to sustain Turbo Boost for very long, but at least the Core i9 in the Zenbook UX580 can maintain base clock rates when under heavy processing load. With such high core temperatures in the 90 C range, however, it's no wonder that the same i9 CPU in the even thinner MacBook Pro is getting a lot of negative press for its supposed throttling behavior.
https://www.notebookcheck.net/The-wacky-dual-screen-Asus-Zenbook-does-Core-i9-better-than-the-MacBook-Pro.317558.0.html