I think I saw this discussion on the forum before. It seemed that they either were tied or the 1650S was slightly better. But the 1650S only has 4GB VRAM, while the 590 has 8GB. I'm wondering if that would be a limitation for using the highest graphic settings*? It would be used with an FX-8350 (don't say it) @ 4.7GHz with 16GB DDR3 1866MHz RAM. The power supply is not an issue. Games would be played at 1080p/60 hz, but a new 1440p/???hz monitor may be in the near future, if that would make a difference.
* single player only
* single player only