In terms of overall gaming performance, the graphical capabilities of the Intel 865G are massively better than the AMD Radeon RX 490 8GB.

The RX 490 was released over three years more recently than the 865G, and so the RX 490 is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the 865G when running the latest games.

Both GPUs exhibit very poor performance, so rather than upgrading from one to the other you should consider looking at more powerful GPUs. Neither of these will be able to run the latest games in any playable way.

The RX 490 has 8176 MB more video memory than the 865G, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the RX 490 also has superior memory performance overall.

The RX 490 has 1024 GB/sec greater memory bandwidth than the 865G, which means that the memory performance of the RX 490 is massively better than the 865G.

The RX 490 has 4096 Shader Processing Units but the 865G does not have an entry, so the two GPUs cannot be reliably compared in this area.

The Radeon RX 490 8GB requires 225 Watts to run and the 865G requires 13 Watts. We would recommend a PSU with at least 550 Watts for the RX 490. The RX 490 requires 212 Watts more than the 865G to run. The difference is significant enough that the RX 490 may have an adverse affect on your yearly electricity bills in comparison to the 865G.