always change to default date/time setting

hail to everyone!

lately, when i turn on my computer, I changed the date/time setting into current time.
my problem is...every time i turn off my computer, remove all the cables/connection(mouse, keyboard, powerchord, monitor cable), then after several minutes, i put it back all the cables then power on, the same it goes back again to default date/time setting that's why i need again to change the date/time setting into current time. anyone who can help me? do i need to change my cmos battery?

thanks in advance!

yes , you need to change the CMOS battery . the always change to default date/time setting is for bad Battery.

^ Oh I see..thank you very much to you Smithsam.