It is possible but flashing bios has risk.  The startup error you encounter is not a strong reason to flash/update bios, but if you want to give it a try and are willing to take the risk of bricking the motherboard, take a deep breath and pray it might work.  however, there is also a chance that after a bios flash, the error may persist.  other people may think the motherboard is bad.  basically if the pc is still working except for the error I suggest just use it for its remaining life.  but if you think it is good time to move on to a newer pc then do whatever you like to experiment with the 780dt.
hi   I have a big problem with the Dell Optiplex 780. After replacing the CMOS battery, I keep getting "Alert! System Battery voltage is low" message. I have tried methods from the manuals such as: [URL] but that didn't help. Does anyone know how to fix this?  
Dell Optiplex 780DT "Alert! System Battery voltage is low" issue.