That ITX version of the card appears to run at stock clocks, but a factory-overclocked RX 570 would not be much more than a few percent faster in games. At least going by this review, it looks like that model has the potential to overclock pretty well though, faster than the factory clocks of an OC model, though overclocking potential can vary from one card to the next, and your results may vary...
Having analysed a few of the new AMD RX 500-series cards since launch, today our attention turns bac
www.kitguru.net
So, I wouldn't try any risky BIOS flash, when you can likely achieve faster results via software overclocking.