Tools -> Auto-configuration Wizard.
That's supposed to figure out the "best" settings for your specific hardware (*), and the "best" streaming quality for your specific internet connection. Of course, with any automated tool, it's only as good as the people thought ahead who made it, but it'll still get you into an "okay" ballpark, and you can watch your system load and tweak from there. (high load is okay, as long as it's constant, and still leaves *some* room for random incidentals)
You might try running the wizard twice - once all by itself, and once with a resource-intensive game running - and compare what it comes up with.
(*) Including possibly bad parts of the silicon die that were permanently disabled from the factory and sold for cheaper. Hardware yield is surprisingly low, and the actual output quality is the result of testing and selection, not the original manufacturing.
And counterfeiting is a thing too, unfortunately, where only the superficial appearance is preserved - both physically and to an OS if applicable - but it's grossly and often debilitatingly cheaper "under the hood". It's kind of a big deal in the electronics engineering world, especially with such complex supply chains that it's really difficult to know the ultimate source...and the effects range all the way from indistinguishable to weird bugs to complete system failure and everything in between.
So what do you *really* have? And what is it *really* capable of? The wizard will give you a better first attempt than we can by guessing and assuming, because it measures what it can actually get away with on that specific chip.