The BIOS, or basic input/output system, is responsible for controlling low-level settings and initializing your hardware when your computer boots up. You're probably most familiar with it as that settings program you can access if you smash the Delete or F1 key while your PC's booting up, getting some frustration out in the process. But the CMOS chip that keeps these settings was traditionally volatile memory, meaning all of these settings would be lost as soon as power was taken away. And since many people don't just leave their computers on 24/7, manufacturers put a coin battery on the motherboard to ensure the settings wouldn't just disappear if someone trips over the power cord or does a magic spell. But fast-forward to modern times, and it turns out that motherboard manufacturers don't use CMOS for BIOS settings anymore, partly because those old CMOS chips only held 128 bytes. But today's systems need to store lots more BIOS data, so, instead, they just choose a chip with non-volatile RAM, or NVRAM, that not only has a higher capacity, but can store data persistently, even if there's no power going to the board.
So, what's the point of still having a battery then, other than sentimental reasons, of course? We'll tell you right after we thank MSI for sponsoring this video. MSI's MEG CoreLiquid S360 all-in-one liquid CPU cooler is a great fit for cooling your 12th gen Intel CPU. It comes equipped with MSI's innovative MEG Silent Gale P12 gaming fans, and it also has a 2.4 inch IPS display capable of displaying hardware information, photos, videos, and even the weather, whatever you want, on your cooler. Plus, it's LGA 1700 compatible right outta the box. So learn more at the links below. So the reason there's still a CMOS battery is because there's still a CMOS chip. But instead of handling the BIOS, nowadays, it's mostly just responsible for timekeeping. Just like a regular old wristwatch, your computer needs power of some sort if you want to keep accurate time.
So that battery ensures your computer's clock will tick away properly, even if you've left it unplugged for an extended period. And the fact that the lithium cell looks like the battery you'd put in your watch is just a nice bonus. But interestingly, many servers can keep time accurately without a CMOS battery, even if the power goes out. Instead of using a CMOS chip to keep time locally, servers often connect to an NTP server at boot time. NTP stands for network time protocol, which is used to connect to a different server over the internet to fetch the time accurately.This isn't commonly used on home PCs, though, so that little battery on your motherboard is still quite important. In fact, if you remove it, you'll probably find that your BIOS settings will still reset, just like they did in the old days. I'm assuming because of tradition. (chuckles) Just kidding, that was a joke. But actually, not really. Because people were so used to removing the battery as a means of resetting the BIOS for so long, most PC manufacturers simply kept this functionality in place as an easy way to clear settings. Of course, there are a good number of motherboards out there that feature a clear CMOS button, either on the board itself or on the rear IO, that will also reset your BIOS settings, though its name is technically a misnomer now.
The reason they kept the terminology was, again, because folks have just been so used to using CMOS as a synonym for BIOS, that the name just stuck. And although all this may be a little confusing, the good news is that the CMOS battery isn't something you have to worry about very often. They typically last for years before they might need to be replaced. But you might wanna have a copy of your BIOS setting saved somewhere anyways, especially if you're the type of person to spend hours getting your RAM timings just right. You can't get that time back, but you might as well have your BIOS settings.
