AFAIK from reading and looking at design schematics, the main regulator or w/e it is is only capable of around 20A output. We may be gettin pretty close to that on just stock overclocks...
So, overvolting safely may be out of the question.
Why you are saying is capable of only 20A?
Grr, I cant remember where yifu posted the design schematics. But the one that shows the layout for each miner board, shows in the VRM section. The main controller chip .. is it a TI or something? Look it up and its max output was like 20amps
Limit for IC is only a "soft" limit. From IC's point of view, it's more up to its ability to drive gate and Miller capacitance of output transistors.