The Radeon RX 5500 XT is bottlenecked by PCIe 3.0
While you may think that the recently launched Radeon RX 5500 XT would be a great drop-in upgrade for your ageing rig, it seems like there’s more to the story. As we have previously reported, the Radeon RX 5500 series is limited to a PCIe 4.0 x8 interface and that is apparently a bottleneck.
Tests by PCGH revealed quite a bit less performance when running the cards with a PCIe 3.0 system, especially on the Radeon RX 5500 XT 4GB variant. The lesser VRAM may have resulted in the card having to rely on shuttling data from the system memory to the card over the PCIe interface, and thus with half the bandwidth with PCIe 3.0 versus PCIe 4.0, you run into performance issues.
This is a rather new finding, as PCIe 3.0 x8 has never been found to be a huge bottleneck even for flagship cards like the GeForce GTX 1080 Ti and the likes of it. But then again, I don’t remember seeing a card designed for a 8-lane PCIe interface either, so this is quite a unique issue that’s affecting the Radeon RX 5500 XT.
Whatever the issue, the 8GB variant of the Radeon RX 5500 XT is also affected, although to a much lesser degree. Most of the cards here in Malaysia are the 8GB variant, so you would probably not encounter that much of an issue with them.
With that said, Hardware Unboxed’s testing revealed a smaller difference in performance between PCIe 3.0 and PCIe 4.0, although there is still noticeably lower performance when running the Radeon RX 5500 XT 4GB over a PCIe 3.0 interface. It’s also worth noting that Hardware Unboxed decided to run with less taxing graphics settings, which may have not taxed the frame buffer on the card nearly as much as PCGH’s testing.
Pokdepinion: It doesn’t really make sense to pair a Radeon RX 5500 XT 4GB with an X570 board, so I would think AMD released this card knowing full well you would run into these kind of issues…
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