What 2 do if I forget the CMOS-password?

Answer 1

pop out the battery on the motherboard then put it back in. This will clear out the password. It is a little coin battery on the motherboard, like a watch battery pops out really easy.

Answer 2

With regard to everybody who answered that the questioner should remove the battery. On most newer systems (i.e. last 10 years), that won't work as the only component using the battery in the clock. Everything else in the BIOS (including the password) is save using NVRAM that doesn't require power to retain it's information.

In most cases, there is a BIOS reset jumper somewhere on the mainboard. On recent systems (last 5 years) they've started labeling the jumper (usually along the lines of BIOS CLR). You should consult the manual for the mainboard. If you don't have it, search for it (Google, Yahoo, etc.). Manuals are usually available for free online.

The sequence usually works like this:

Lost BIOS password
Short jumper
Turn on computer
Count to 10
Turn off computer (at the plug)
Unshort the jumper
Turn on the computer
Reenter all of the BIOS settings that it cleared for you.

Answer 3

You can take the CMOS battery out and replace it to reset it to the default password, which will be no password.