Ok we need to slow down a notch as this issue can be specific or from an array of situations.
1) First and foremost. When you boot your PC (Turn it on). what happens in 100% of cases. Does it turn on or not? As I read it in your post, I want to assume that you have a major issue with your PSU that may be DOA; therefore switch for friend spare PSU and/or send it back for an exchange. The motherboard battery may be the cause but I really do not think so!
If the PC turn on....:
2) Check and Re check again with your biostar manual + go to biostar forum if you have doubts about any connection from wiring connection to jumpers (if any), to memory module types and genre and see what comes in their forum.
3)what is your PSU brand, wattage and model
4) Look, it sounds to me to be either way an issue in the bios settings for memory and/or a bios setting for your hdd in case if I misunderstood the deal about the issue of not powering your PC100% of time.