The Nvidia GTX 1030 has no encode capability. Plex transcodes all video to H.264, so you need a GPU that encodes to that format.
You also want a GPU that decodes H.265 12-bit video (for HDR video).
For Nvidia, that means a GTX 1050 or better. See NVDEC info in Nvidia Encode/Decode Matrix for details.
For Nvidia transcoding performance info see: https://www.elpamsoft.com/?p=Plex-Hardware-Transcoding
Nvidia limits their consumer GPU cards to two simultaneous decodes. This can be bypassed with hacked drivers. See elpamsoft page for details.
Ryzens generally provide a much better “bang for the buck” than Intel. However, if you need hardware accelerated transcoding, the lack of integrated graphics may change the value proposition, since you have to figure in the cost of the GPU card.
If you do not need a discrete GPU for gaming, etc, Intel CPUs with UHD graphics are very capable when it comes to transcoding video.
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