In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce RTX 2080 Ti SLI are massively better than the AMD Radeon R9 390 Sapphire Nitro 8GB Edition.

The RTX 2080 Ti has a 340 MHz higher core clock speed and 112 more Texture Mapping Units than the R9 390. This results in the RTX 2080 Ti providing 205.6 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 RTX 2080 Ti has a 340 MHz higher core clock speed and 24 more Render Output Units than the R9 390. This results in the RTX 2080 Ti providing 54.2 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 RTX 2080 Ti was released over three years more recently than the R9 390, and so the RTX 2080 Ti is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the R9 390 when running the latest games.

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 RTX 2080 Ti has 3072 MB more video memory than the R9 390, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the RTX 2080 Ti also has superior memory performance overall.

The RTX 2080 Ti has 232 GB/sec greater memory bandwidth than the R9 390, which means that the memory performance of the RTX 2080 Ti is massively better than the R9 390.

The GeForce RTX 2080 Ti SLI has 4352 Shader Processing Units and the Radeon R9 390 Sapphire Nitro 8GB Edition has 2560. However, the actual shader performance of the RTX 2080 Ti is 7116 and the actual shader performance of the R9 390 is 2198. The RTX 2080 Ti having 4918 better shader performance and an altogether better performance when taking into account other relevant data means that the RTX 2080 Ti delivers a massively smoother and more efficient experience when processing graphical data than the R9 390.

The RTX 2080 Ti transistor size technology is 16 nm (nanometers) smaller than the R9 390. This means that the RTX 2080 Ti is expected to run slightly cooler and achieve higher clock frequencies than the R9 390.

The GeForce RTX 2080 Ti SLI requires 260 Watts to run and the Radeon R9 390 Sapphire Nitro 8GB Edition requires 375 Watts. We would recommend a PSU with at least 650 Watts for the RTX 2080 Ti and a PSU with at least 750 Watts for the R9 390. The R9 390 requires 115 Watts more than the RTX 2080 Ti to run. The difference is significant enough that the R9 390 may have an adverse affect on your yearly electricity bills in comparison to the RTX 2080 Ti.