In terms of overall gaming performance, the graphical capabilities of the AMD Radeon RX 480X 4GB are noticeably better than the AMD Radeon R9 390X XFX Double Dissipation Black 8GB Edition.

The RX 480X has a 60 MHz higher core clock speed and 80 more Texture Mapping Units than the R9 390X. This results in the RX 480X providing 102.6 GTexel/s better texturing performance. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The RX 480X has a 60 MHz higher core clock speed and 64 more Render Output Units than the R9 390X. This results in the RX 480X providing 77.4 GPixel/s better pixeling performance. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The RX 480X was released over a year more recently than the R9 390X, and so the RX 480X is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the R9 390X.

Both GPUs exhibit very powerful performance, so it probably isn't worth upgrading from one to the other, as both are capable of running even the most demanding games at the highest settings.

The R9 390X has 4096 MB more video memory than the RX 480X, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the R9 390X also has superior memory performance overall.

The R9 390X has 384 GB/sec greater memory bandwidth than the RX 480X, which means that the memory performance of the R9 390X is massively better than the RX 480X.

The Radeon RX 480X 4GB has 4096 Shader Processing Units and the Radeon R9 390X XFX Double Dissipation Black 8GB Edition has 2816. However, the actual shader performance of the RX 480X is 5325 and the actual shader performance of the R9 390X is 2609. The RX 480X having 2716 better shader performance is not particularly notable, as altogether the R9 390X performs better when taking into account other relevant data.

The RX 480X transistor size technology is 14 nm (nanometers) smaller than the R9 390X. This means that the RX 480X is expected to run slightly cooler and achieve higher clock frequencies than the R9 390X.

The Radeon RX 480X 4GB requires 175 Watts to run and the Radeon R9 390X XFX Double Dissipation Black 8GB Edition requires 300 Watts. We would recommend a PSU with at least 500 Watts for the RX 480X and a PSU with at least 750 Watts for the R9 390X. The R9 390X requires 125 Watts more than the RX 480X to run. The difference is significant enough that the R9 390X may have an adverse affect on your yearly electricity bills in comparison to the RX 480X.