TechPowerUp recently tested the new AMD Radeon RX 6400 GPU on the slower PCIe 3.0 interface to measure significant declines in performance compared to PCIe 4.0 and found that this is due to the unorthodox GPU configuration of only four PCIe lanes. On average, the drop in productivity was over 14%, depending on the resolution.
AMD’s Radeon RX 6400 is the company’s latest entry-level graphics processor for the desktop market, including AMD’s ultra-small Navi 24 matrix, originally for laptops. Like its older brother, the Radeon RX 6500 XT, this GPU has only four PCIe 4.0 tapes as a cost-cutting measure. The Radeon RX 6400 features a rough 13% reduction in the number of cores and memory bandwidth compared to the Radeon RX 6500 XT. The graphics card has only 768 cores and 128 GBps of memory bandwidth, thanks to the reduction of GDDR6 speeds to 16 Gbps. However, the memory capacity remains the same – 4GB. But the main strength of the Radeon RX 6400 is its power consumption. It has half the power of the Radeon RX 6500 XT for 53 W, which makes this GPU very useful in small systems with budget systems that cannot power higher-end GPUs with auxiliary power.
In the 24 games tested by TechPowerUp, the Radeon RX 6400 running on PCIe 3.0 has an average of 14% drop in performance on both 1080P and 1440P cumulatively compared to PCIe 4.0. 4K results were even worse, with a 23% deficit in productivity. However, we doubt that this will be of much importance, as the Radeon RX 6400 offers FPS, which cannot be played in both PCIe generations.
Some of the worst offenders are included F1 2021 and Eternal doom, which saw a 79% and 43% difference in performance at 1080P. Fortunately, almost all the other titles tested were in the range of 14% or less, but these two games specifically show how much PCIe-intensive bandwidth can really become for some gaming engines.
Testing of TechPowerUp for Radeon RX 6500 XT showed almost the same resultsshowing a 13% performance deficit for PCIe 3.0 compared to PCIe 4.0. The Radeon RX 6400 can’t escape the limitations of the Navi 24 for four lanes, even if the GPU itself is slower. The Radeon RX 6400’s PCIe 3.0 was almost 20% slower than the GeForce GTX 1650, which runs on the same PCIe 3.0 interface and runs a much healthier x16-band configuration. However, when installed on a PCIe 4.0 interface, the Radeon RX 6400 works similarly to the GeForce GTX 1650.
Users watching the Radeon RX 6400 need a PCIe 4.0 platform to avoid a significant drop in PCIe 3.0 performance. The biggest problem is that most systems are still on PCIe 3.0, and users who are likely to buy the Radeon RX 6400 are on an old system. If you don’t have access to PCIe 4.0, a better alternative is Nvidia’s GeForce GTX 1650 or even the older Radeon RX 570, which is faster than the Radeon RX 6400 and doesn’t require PCIe 4.0 to unlock its full performance.