It is not a secret that the default firmware and even settings for many of the ASIC miners that come out from the manufacturers are hardly with the best/optimal settings and often they are also limited in what you can tweak yourself. So some more advanced users take the matter in their hands in order to further optimize for performance and or stability and reliability and even add extra features that help owners of the devices to get better profit or higher profit for example. One such case is the Antminer D3 Blissz Modified Firmware for the X11 ASICs being produces by Bitmain that you might want to give a try if you have even at least one of these ASIC miners.
The custom firmware promises up to 20% lower power usage and some extra features such as ASIC voltage settings per chain as well as the ability to overclock or underclock per chain as well as more control on fan operational speeds. There are some usability improvements in the interface to make it easier and clear to use as well as some slight performance improvements as well to make it more stable and reliable in terms of operation including cgminer binary optimizations.
Do note that this is an experimental custom firmware and using it might void your warranty. Also note that it comes with built-in 1.5% developer fee built-in, so do have that in mind, although the improvements if working as promised are well worth the dev fee. The good thing is that even if you don’t like something or it does not work as expected flashing back the original firmware is as easy as installing the custom one, so you can quickly give it a go and if you don’t like the results to get back to the original.