Asus G73jh-A1 Boot/Battery Problem

My Asus G73jh wont boot with battery alone. It only booths up with adapter plugged in. After booting i unplug it and it runs with battery reading over 90%. When the battery reaches about 30% the unit cuts off (not shut down normally). I recently noticed that when I remove my internal BD rom drive the unit booths on the battery without needing to plug in the ac adapter.
Is this a battery problem a software problem or a motherboard problem.
My other problem is if i install realtek sound drivers i get loud static noise when sounds are supposed to be played.
I was thinking of replacing my motherboard because in all my investigating i believe the noise is a motherboard problem but the boards available are the same revision 2 as mine.
Should I just buy another laptop?

 

Try resetting it first. I believe you can take the battery out, so unplug it, remove the battery and hold down the power button for around 30 seconds. If the controller isn't reporting battery charge level correctly it could cause this sort of problem.

 

I tried that and it did not help. I bought the battery used but the shop claimed that it was tested and functioning properly. It is an aftermarket battery.

 

Might also check the contacts and clean them with alcohol.