Nonvolatile BIOS memory refers to a small memory on PC motherboards that is used to store BIOS settings. It is traditionally called CMOS RAM because it uses a volatile, low-power complementary metal-oxide-semiconductor SRAM powered by a small "CMOS" battery when system and standby power is off.

What does CMOS reset do?

Clearing the CMOS resets your BIOS settings back to their factory default state. In most cases, you can clear the CMOS from within the BIOS menu. In some cases, you may have to open your computer's case.

Does resetting CMOS delete files?

It returns BIOS settings to default values. This has nothing to do with pictures or any saved programs or files.