Introduction

AMD today released the Radeon RX 6500 XT graphics card to market, an entry-mainstream product for AAA gaming at 1080p with FidelityFX Super Resolution (FSR) enabled, and fairly high eye-candy. You can read all about it in our review of the card. In this article, we're studying the impact of AMD's interesting design choice to go with an extremely narrow PCI-Express x4 interface on the RX 6500 XT.



We normally reserve PCI-Express scaling articles for our very top-end graphics cards as they give us insights into how GPUs have advanced and what their bus bandwidth demands are. However, over the last couple of AMD Radeon GPU generations, we've been doing such articles for mid-range AMD GPUs. The Radeon RX 550 started the trend of 8-lane PCIe interfaces for mid-range graphics cards. The card looks like it has a PCI-Express x16 interface, but only wiring for 8 lanes. The company doubled down on this with the subsequent RX 5500 XT and went a segment further up this generation, with the RX 6600 XT and RX 6600. This forced us to do a similar article for the RX 6600 XT, which you can read here. For the new RX 6500 XT and RX 6400, the company narrowed down the PCIe interface further, to just 4 lanes. That's PCI-Express 4.0 x4.



PCI-Express 4.0 x4 on its own is a fair amount of bandwidth—comparable to PCI-Express 2.0 x16, with 8 GB/s per direction. For a mainstream GPU like the RX 6500 XT, or the entry-level RX 6400, it works just fine. The trouble is that PCI-Express Gen4 isn't as well proliferated as AMD likes to think. Only the Ryzen 3000 Zen 2 and Ryzen 5000X Zen 3, when paired with AMD B550 or X570 motherboards, support it—you can discount all the instances where these chips are paired with 400-series chipsets, or even the entry-level A520. On the Intel side of things, only the 11th Gen Core Rocket Lake, and newer 12th Gen Core Alder Lake support it. Intel never made 11th Gen Core i3. This card will support all previous generations of PCIe on older processors, but the PCIe lane count will remain 4.

In this PCI-Express scaling article, we will put the Radeon RX 6500 XT through older generations of PCI-Express to illustrate performance losses (if any).