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).

Test System

Benchmark scores in other reviews are only comparable when this exact same configuration is used.

• All games and cards are tested with the drivers listed above—no performance results were recycled between test systems. Only this exact system with exactly the same configuration is used.
• All graphics cards are tested using the same game version.
• All games are set to their highest quality setting unless indicated otherwise.
• AA and AF are applied via in-game settings, not via the driver's control panel.
• Before starting measurements, we heat up the card for each test to ensure a steady state is tested. This ensures that the card won't boost to unrealistically high clocks for only a few seconds until it heats up, as that doesn't represent prolonged gameplay.

Each game is tested at these screen resolutions:

• 1920x1080: Most popular monitor resolution.
• 2560x1440: Intermediary resolution between Full HD and 4K, with reasonable performance requirements.
• 3840x2160: 4K Ultra HD resolution, available on the latest high-end monitors.

Assassin's Creed Valhalla

Released: 2020 — API: DirectX 12 — Engine: AnvilNext 2.0

It is the year 873 AD, the most violent period in Norwegian history. A Viking clan leader takes a group of refugee warriors across the seas to medieval England, where they set up camp as barely welcome migrants to the local kingdoms. You form alliances with local lords and raid Saxon strongholds for resources to build and grow your settlement. The historic cities of Winchester, London, and York, as well as vast landscapes of Norway, are brought to life in this outstanding Assassin's Creed experience.

Based on the same AnvilNext 2 engine that powers other Ubisoft titles, Assassin's Creed Valhalla takes advantage of DirectX 12 and offers outstanding visuals that look amazing even without ray tracing. We tested at the highest details using our own custom test scene.

Battlefield V

Released: 2018 — API: DirectX 11 — Engine: Frostbite

Battlefield V is the latest chapter in EA's smash-hit online multiplayer shooter franchise. The series has come full circle since its debut "1942" and is set in World War II. The single-player campaign is broken up into bite-sized chunks called War Stories. Much like Battlefield 1, each depicts a different theater of war, a different protagonist, and a different mission. The multi-player builds on the franchise's core strengths with the addition of new game modes and room for a future mode rivaling battle royale.

Based on the Frostbite 3 engine by EA-DICE, Battlefield V supports both DirectX 11 and DirectX 12, and newer technologies, such as DirectX ray tracing. In this particular test, we used DirectX 11 as that's the API used by the majority of players.