Which chip is a motherboard battery powering?

Factual Questions
1

I know that the battery is not powering the BIOS chip. The BIOS itself is non-volatile and doesn’t require any power to retain data.

Therefore it must be some other chip that is powered from that CR20xx cell.

2

CMOS RAM.

3

My understanding is that it powers the CMOS RAM, which retains the current date and time as well as any user-configured BIOS settings. Motherboards I’ve played around with have 640k of standalone CMOS RAM, but I think some have that memory wrapped up into another component (memory controller?).

Edit: BAH!

4

It’s for the RTC (real-time clock).

The OP already covered the memory. Battery-backed CMOS isn’t used anymore.

5

Thanks!

From that link:

So the battery powers the southbridge.

6

The battery powers a tiny part of that chip when the main power is off.