Since you’re contemplating a Plex Pass, consider using a 8th Gen+ i7/i9 Intel CPU and no graphics card. 8th Gen+ CPUs have UHD Graphics 630, the most recent version of Intel’s Quick Sync graphics. Avoid the CPUs ending in “F,” as they have no onboard graphics (ex: i7-9700KF).
Spend the extra money on the CPU instead of a graphics card.
If you do go with a graphics card, note that AMD graphics cards not supported for hardware acceleration in Linux.
Here’s some good info on Nvidia transcoding capability: https://www.elpamsoft.com/?p=Plex-Hardware-Transcoding
This (long) thread has good info as well.
Nvidia GTX graphics cards are limited, by Nvidia, to two simultaneous encodes. Hacked drivers are available to remove this limit. No idea how well they work or if they work for Linux.
Nvidia Quadro cards have no pre-set limit on encodes. Performance is limited by available memory.
So…
If you go with Intel on-board graphics, avoid the “F” CPUs and go with UHD 630 graphics.
If you go with a GTX card, you’ll want one that decodes H.265. This means a 1050 or better. From what I’ve read, Nvidia improved the encoder quality with the 16xx cards, so you may want to go with a 1650 or better.
For a Quadro card, you’ll want a P2000 or better. P1000 & lower are limited like the GTX cards.
The Nvidia support matrix has additional details:
