Understanding the Performance Impact of FSR 4 INT8 on RDNA 2 and RDNA 3 GPUs
Introduction to FSR 4 and its Performance on Older Architectures
AMD's FidelityFX Super Resolution (FSR) technology has been a cornerstone for enhancing gaming performance by intelligently upscaling lower-resolution images. With the advent of FSR 4, particularly its INT8 implementation, new performance considerations have emerged for users with RDNA 2 and RDNA 3 graphics processing units (GPUs). Recent analyses and benchmarks suggest a noticeable performance impact on these older architectures when adopting the latest iteration of AMD's upscaling technology.
Performance Benchmarks: RDNA 2 and RDNA 3 vs. FSR 4 INT8
Independent testing has revealed that while FSR 4 can be run on RDNA 2 and RDNA 3 GPUs, the performance trade-offs are significant when compared to previous versions like FSR 3.1. Specifically, GPUs such as the Radeon RX 7800 XT (RDNA 3) and the RX 6800 XT (RDNA 2) have shown a performance reduction of approximately 9-13% in average frames per second (FPS) when using FSR 4 in Quality mode, relative to FSR 3.1 in the same mode.
For context, a newer GPU like the Radeon RX 9060 XT (part of the RDNA 4 family) exhibited a much smaller performance difference, around 3%, when transitioning from FSR 3.1 to FSR 4 in Quality mode at a 1440p resolution. This disparity underscores the architectural differences and optimizations present in newer hardware.
Understanding the Performance Discrepancy
The performance decrease observed on RDNA 2 and RDNA 3 hardware is largely attributed to the underlying architecture and the specific instructions FSR 4 leverages. FSR 4 is designed to take advantage of new Wave Matrix Multiply-Accumulate (WMMA) instructions, which are native to the upcoming RDNA 4 architecture. Older GPUs, lacking these dedicated hardware units, must resort to emulating these operations using more general-purpose integer units. This emulation process is inherently less efficient and consumes more computational resources, leading to the observed drop in FPS.
In scenarios where FSR 4 was tested in Performance mode, the RX 7800 XT and RX 6800 XT were able to show a slight improvement of about 5% over FSR 3.1. However, when directly comparing FSR 4 Performance preset against FSR 3.1 Performance preset, the regression was around 12-13%, indicating that the performance cost becomes more apparent at lower quality settings as well.
Visual Quality: FSR 4 INT8 vs. FSR 3.1
Despite the performance cost, the INT8 version of FSR 4 does offer visual improvements over FSR 3.1. Reports suggest that the difference in visual quality can be noticeable, varying from game to game and scene to scene. Generally, the official FP8 version of FSR 4 is expected to provide superior visual fidelity, which is a common expectation with newer iterations of upscaling technologies. The INT8 version, while potentially less refined than FP8, still presents a step up in image quality compared to its predecessor.
The Role of Architecture: RDNA 4 and Beyond
The performance implications highlight the importance of hardware architecture in the adoption of new software technologies. AMD
AI Summary
Recent benchmarks indicate that AMD's RDNA 2 and RDNA 3 GPUs experience a performance reduction of approximately 10% when utilizing the INT8 version of FSR 4, especially when compared to FSR 3.1. While the visual quality improvements of FSR 4 INT8 over FSR 3.1 are noted as significant, the performance cost on older architectures is more pronounced than on newer ones. Specifically, the RX 7800 XT and RX 6800 XT showed a 9-10% decrease in average FPS in Quality mode. In Performance mode, these older cards could outperform FSR 3.1 by about 5%, but when directly compared, the difference was around 12-13%. This performance hit is attributed to the older GPUs lacking the native Wave Matrix Multiply-Accumulate (WMMA) instructions that FSR 4 leverages, forcing them to rely on less efficient emulation methods. Newer RDNA 4 GPUs are expected to have a much smaller performance impact, estimated at around 2-4%. The context also touches upon AMD's RDNA 4 architecture, its new ray tracing engine, and the upcoming RX 9000 series, which will fully support FSR 4 with its advanced AI and FP8 capabilities, highlighting a generational shift in how these technologies are implemented and perform.