I recommend to leave BIOS as it is. Put all things together, install Windows and use PC a while. That way you make sure that PC (the way you built it) is working properly. And if it does work as expected, I see no reason to update BIOS.
I think it's more important that you have latest chipset drivers ready (on USB stick, for example). You should install this driver just after installing Windows -same goes for graphic card driver. But then, PC should work even if these drivers are not installed (when installing Windows, "default" drivers will be installed anyway).
I think it's more important that you have latest chipset drivers ready (on USB stick, for example). You should install this driver just after installing Windows -same goes for graphic card driver. But then, PC should work even if these drivers are not installed (when installing Windows, "default" drivers will be installed anyway).