Well Yes, But Actually …
The RX 6400 release was not exactly exciting, considering it competes with cards like the RX 480 (2016) and RX 570 (2017). To be fair, those were the higher end of those graphics families which the RX 6400 certainly is not. Then again the RX 480 launched at $200 for the 4GB and $240 for the 8GB while the RX 570 had an MRSP of $170, while the RX 6400 will cost you $150. That goes to show you how quickly pricing has changed compared to relative performance.
If you want to compare it to NVIDIA, the closest that The Guru of 3D had to test was the $380 GTX 1060 (2016) which the RX 6400 can sometimes beat and the $330 GTX 970 (2014) which it beats. So what could you compare this card to, other than ancient hardware? How about Intel’s Arc 380?
When the two cards fight it out at 1080p with resizable BAR enabled, the RX 6400 is sometimes better and sometimes not, with the average performance being pretty much equal. If you increase the resolution, neither card games well but the Intel Arc 380 noticeably outperforms the RX 6400. This is important because of the number of outputs the Arc card has; you might not be gaming but instead running multiple monitors that need to be powered.
The A380 is $10 cheaper and has three DP and one HDMI, while the Radeon RX 6400 only has one of each. Considering that, it seems we have one of the first wins for Intel’s Arc. It’s hard to recommend the RX 6400, except for certain specific games it can actually beat the Intel GPU on.
Meet AMD's Radeon RX 6400. It has 4GB of 64-bit RAM and a whiff of Inifinity Cache (16MB L3). This card might operate at Radeon RX 480 levels when connected to a PCIe Gen x4 connection (3.0/4.0)