AMD Radeon RX 5500 XT 8GB Linux Gaming Performance
With Deus Ex: Mankind Divided, one of the most demanding OpenGL-rendered native Linux games, the 8GB of RAM didn't help the RX 5500 series performance but came in just in line with the 4GB version including for minimum/maximum FPS.
The additional GDDR6 video memory wasn't enough to cause any real difference in the power efficiency.
For the F1 2017 Linux-native racing game, the RX 5500 XT performance was the same between the 4GB and 8GB versions.