Obviously you're used to nvidia/windows way on doing things. You are on linux now. Opensource is the whole philosophy. So yes, please just use the free/opensource drivers that come bundled with your favorite distro. This is the preferred way to go with AMD hardware.

Here's the Radeon 7 with opensource amd drivers: https://www.phoronix.com/scan.php?page=article&item=radeon-vii-linux&num=1

Benchmarks between different mesa versions, so using an ubuntu ppa such as oibaf or pandoka does matter to get the newest stack and best performance: https://www.phoronix.com/scan.php?page=article&item=mesa182-4-july&num=1

And.. the icing on a cake, the comparison between opensource radeonsi and closed source (amdgpu-pro/radeon software aka the one you've downloaded): https://www.phoronix.com/scan.php?page=article&item=radeon-software-1820&num=1

As you can see, apart from the fact that the closed source one is kind of behind in performance, it also has some issues running some of the benchmarks (aka it crashes), hence your experience.

So, in conclusion, yes. For polaris, on linux, use opensource drivers. If you've messed up the distro with alot of experiments and closed source driver installations, perhaps it would be better a fresh install and just use mesa/llvm packages from pandoka ppa stable with a recent ubuntu mainline kernel.

Goodluck,

Cheers!

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Sent from mobile, apologies for typos.