Asus doesn't even test basic features, nevermind the extra ones. I have the 2017 Zephyrus GX501, which came with a Nvidia GTX 1080 which introduced HDMI 2.0 support. The Asus Zephyrus marketing material is boasting about HDMI 2.0 capability, the manual talks about HDMI 2.0 etc. However, in reality the device is limited to HDMI 1.4 bandwidth.
The problem isn't limited to some units, there was plenty of discussion online of this issue at the time of release. [1]
Asus never recalled, fixed, or even responded to the issue. Indeed, even the marketing page [2] still talks about how you can use HDMI 2.0 to connect 4K TVs at 60Hz.
It was also an interesting showcase of laptop reviewer incompetence. All the reviews just regurgitated Asus marketing material on how it has HDMI 2.0, but apparently nobody actually tested it.
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[1] https://rog-forum.asus.com/t5/rog-zephyrus-series/gx501-zeph...
[2] https://rog.asus.com/laptops/rog-zephyrus/rog-zephyrus-gx501...
Imagine if we had strong consumer protection laws. Companies would fear claiming HDMI 2.0 that was really HDMI 1.2. Instead they just figure “meh! If anyone complains we’ll let them return it.”