Also, as stated in my first post, AMD Radeon Software doesn't work for me. I tried downloading it and it doesn't open when I try to open it.
Sorry i missed this. Asus provides Vega 10 graphics via it's chipset driver. Not sure if Adrenaline properly supports Apu graphics in laptops.
According to faq page for your notebook, how to update chipset driver;
https://www.asus.com/support/FAQ/1039816
Post i saw regarding Adrenaline and notebooks. It's several months old, not sure if anything has changed.
https://community.amd.com/thread/236604
If true, might explain Adrenaline not launching? Kind of useless if you can't optimise settings for the Amd Vega 10 graphics.
Your laptop does support video over USB Type C which has been known to be wired directly to the graphics card if there is one. Not always though (it's difficult to know), but have seen people achieve 144Hz externally using USB Type C instead of Hdmi. Hdmi itself isn't limited but as with some laptops, the Intel's iGPU was limited.
So it might be the same for you. As you said too, Vega controlls Hdmi with GPU crossover, meaning gpu passes frames through the iGPU's graphics controller. Sounds far fetched really but could be possible, the lack of UI for Vega graphics isn't giving you the settings you need.
If your laptop's USB Type C port is controlled exclusively by the Nvidia card, and your TV has Hdmi v1.4, an Active USB Type C to Hdmi cable could make more of a difference in NvidiaCP.
https://www.amazon.com/dp/B0727QQLV2/?tag=linus21-20
What's the model number for your Sansui 24" LED-LCD TV? Id like to check the manual.
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Imho, 24", there's plenty of affordable monitors in that size. Maybe consider?