I have a B550M K motherboard and a Ryzen 7 5700G. The motherboard supports PCIe 4.0, but the 5700G limits the system to PCIe 3.0, and the RTX 5050 would run at x8. Would that bandwidth limitation make the 5050 perform worse than a standard GTX 1080, or would it still be the faster and more capable card overall?
3 Answers
The main concern is VRAM, not the normal PCIe bandwidth difference. If the card has to move data through system memory because its VRAM is full, PCIe 3.0 x8 can cause much larger drops in frame rates and especially 1% lows. With enough VRAM for the game, the PCIe limitation is usually only a modest performance hit.
The 5700G is what limits you to PCIe 3.0; the B550 motherboard itself can support PCIe 4.0 with a suitable processor. Overall, the two GPUs may trade wins depending on the game, so replacing an existing GTX 1080 may not be worthwhile unless you specifically need newer features, better efficiency, or improved performance in your particular games.
PCIe 3.0 x8 probably won't make the RTX 5050 dramatically slower. In most games, it should remain at least competitive with a GTX 1080, and features like DLSS and frame generation can make it more useful in supported titles. The exact result will depend on the game and settings, though.
That is why a simple average-FPS comparison can be misleading. A game may look fine until the card runs out of VRAM, after which stuttering and low-percentile performance can get much worse.