There are multiple issues stopping you from running 4 K at 144 Hz. There's a bit of guesswork here, but
They tested and worked out the panel would do 1080p at 144 Hz. There are examples of panels with slower refresh rates that would overclock to 144 Hz, like some variants of the Yamakasi Catleap.
The bottleneck for faster refresh rates might not be 'just' the panels – there's no common standard that would do 4 K at 120 Hz or better (dp 1.3 systems are just coming out), so there's no practical purpose to monitor hardware that does it.
There's no controller chip that would do 4k120 or better, but someone figured there's a market for different refresh rates if you drop resolutions. My guess is they found the panel controller has the power to do 1080p144.
Monitors can do different refresh rates already – you often drop down to 4k30 on older dp connections, but go back up to 60 as needed. The bottleneck is likely the controller.
In theory, I'd suspect the same panel could do 4 K 144 with the right controller and interface. Since the interfaces and controllers are non-existent, it makes business sense to sell a monitor with high refresh rates (for gamers) and high resolution (for entertainment, I suppose) and let people pick between them.
That makes sense, I'm wondering why this is the only product of its kind that has this dynamic switching option though. I feel skeptical about it, do have experience with this product or similar ones? – Nathan – 2017-05-22T02:43:52.480
Most monitors will have a range of resolutions they support, and no, I'm not familiar with this specific model, as much as the unusual options some of these monitors support – Journeyman Geek – 2017-05-22T04:24:16.850