The full process is described at Overclocking.Guide, users reported success with ASUS and Sapphire cards but it's unlikely the trick will work with every single RX 460 on the market. If you're lucky, your card may have 8 TMUs with 1024 functional stream processors but on a lot of cards these 128 stream processors will be disabled for a good reason. Furthermore, if you use the new ReLive drivers you also need to use this workaround to circumvent the BIOS signature check.
If the trick works, you can expect about 12.5 percent higher performance. Be aware that there's some risk involved, flash at your own risk.