I honestly don't think that installing Linux caused your BIOS to reset. If you can set the BIOS now and if it keeps your settings then it isn't really important. If your BIOS won't keep your settings then it may be that your motherboard's battery is no good. I don't mean to be dismissive. I take a very practical view to system administration. I don't spend a lot of time trying to figure out little quirks if they aren't a problem.
