According to the Gainward website:
Zero RPM fan design is supported for all Gainward GTX 1060 6GB series. Zero RPM fan feature will keep the fans stop under low GPU loading operation, and start to work whenever the GPU temperature raising up. Users will enjoy totally quiet gaming environment with the feature of Zero RPM fan. DrMOS also is used that provides higher power efficiency than normal MOSFET design.
So your GPU card cooling fans should not be running at 25% even with the current, or any version of the BIOS for that card, unless something is wrong as in you do not have sufficient case cooling to supply fresh air into the case and expel heat, so even at idle the card is too hot, or something is not configured correctly.
Make sure you have the latest driver installed after running the DDU to wipe the old drivers, and then make sure you also have Gainward's ExperTool installed as it seems that is what must be used to make adjustments to your card settings. If you've already tried all that and there is still a problem then I'd suggest you contact Gainward and explain to them that you cannot achieve Zero fan with your card while at idle. Perhaps there is a fault with the card itself.