I have a dell laptop inspiron 15,  recently it beeps 5 times on startup meaning to replace to replace the CMOS battery. I found out the battery is soldered in when I took it to GEEK squad.  How can I replace the CMOS battery, or do i have to since everything else works fine, only the loud beeps are annoying.  Dell said I have to replace the MOTHERBOARD, but that is a big expense.  Help.It needs REPLACED...however you decide to do it

Not a User job BTW....get estimates and decide if it's worth it or not.if it only beeps at startup, can you live with that?

the hassle of a flat battery is the laptop will lose date/time and other settings each time it boots - like your boot order and such.
no real biggie and it may not even impact you if the default BIOS settings are what you had/need anyway.
plus Windows will automatically set the date/time once it talks to the time servers.I disagree at one point,,,eventually it will not let the HDD/OS boot properly at all.you may be right, and I haven't seen it get that bad. 
worst I've had is it'll pop up a warning at startup that the BIOS is wrong and hit F1 to enter setup or F2 to continue, something like that.
I've left a laptop do that for years, but MAYBE other BIOS brands are different.