1 00:00:00,000 --> 00:00:05,320 So your desktop computer probably has a big, chunky power supply and a thick, heavy cable 2 00:00:05,320 --> 00:00:08,320 running to the wall to provide all the power it needs. 3 00:00:08,320 --> 00:00:11,640 So have you ever wondered why the heck there's one of those little lithium-coin batteries 4 00:00:11,640 --> 00:00:15,280 sitting in your motherboard? Before we tell you, we'd like to thank Zach Bobroff 5 00:00:15,280 --> 00:00:18,760 of American Megatrends for collaborating with us on this video. 6 00:00:18,760 --> 00:00:22,040 Love you, Zach. So, the battery is there to power something 7 00:00:22,040 --> 00:00:27,440 called a CMOS chip. CMOS stands for Complementary Metal Oxide Semiconductor, 8 00:00:27,440 --> 00:00:31,320 and while that sounds complicated, all you really need to know is that it's a common way 9 00:00:31,320 --> 00:00:35,080 of manufacturing computer chips, used for applications from camera sensors 10 00:00:35,080 --> 00:00:41,280 to analog digital converters to amplifiers. But inside a PC, CMOS has historically been shorthand 11 00:00:41,280 --> 00:00:46,280 for the chip that contained your BIOS settings. The BIOS, or Basic Input Output System, 12 00:00:46,280 --> 00:00:51,400 is responsible for controlling low-level settings and initializing your hardware when your computer boots up. 13 00:00:51,400 --> 00:00:54,480 You're probably most familiar with it as that settings program you can access 14 00:00:54,480 --> 00:00:58,040 if you smash the delete or F1 key while your PC's booting up, 15 00:00:58,080 --> 00:01:02,240 getting some frustration out in the process. But the CMOS chip that keeps these settings 16 00:01:02,240 --> 00:01:06,680 was traditionally volatile memory, meaning all of these settings would be lost 17 00:01:06,680 --> 00:01:10,440 as soon as power was taken away. And since many people don't just leave their computers 18 00:01:10,440 --> 00:01:14,200 on 24-7, manufacturers put a coin battery on the motherboard 19 00:01:14,200 --> 00:01:18,280 to ensure the settings wouldn't just disappear if someone trips over the power cord, 20 00:01:18,280 --> 00:01:22,280 or does a magic spell. But fast forward to modern times, 21 00:01:22,280 --> 00:01:26,840 and it turns out that motherboard manufacturers don't use CMOS for BIOS settings anymore, 22 00:01:26,840 --> 00:01:31,200 partly because those old CMOS chips only held 128 bytes. 23 00:01:31,200 --> 00:01:34,920 But today's systems need to store lots more BIOS data. 24 00:01:34,920 --> 00:01:38,120 So instead, they just choose a chip with non-volatile RAM 25 00:01:38,120 --> 00:01:41,200 or NV RAM that not only has a higher capacity, 26 00:01:41,200 --> 00:01:45,040 but can store data persistently, even if there's no power going to the board. 27 00:01:45,040 --> 00:01:49,920 So what's the point of still having a battery then? Other than sentimental reasons, of course. 28 00:01:49,920 --> 00:01:55,040 So the reason there's still a CMOS battery is because there's still a CMOS chip. 29 00:01:55,040 --> 00:01:59,640 But instead of handling the BIOS, nowadays it's mostly just responsible for timekeeping. 30 00:01:59,640 --> 00:02:03,500 Just like a regular old wristwatch, your computer needs power of some sort 31 00:02:03,500 --> 00:02:07,520 if you wanna keep accurate time. So that battery ensures your computer's clock 32 00:02:07,520 --> 00:02:11,360 will tick away properly, even if you've left it unplugged for an extended period. 33 00:02:11,360 --> 00:02:15,980 And the fact that the lithium cell looks like the battery you'd put in your watch is just a nice bonus. 34 00:02:15,980 --> 00:02:19,320 But interestingly, many servers can keep time accurately 35 00:02:19,320 --> 00:02:24,800 without a CMOS battery, even if the power goes out. Instead of using a CMOS chip to keep time locally, 36 00:02:24,840 --> 00:02:28,480 servers often connect to an NTP server at boot time. 37 00:02:28,480 --> 00:02:32,820 NTP stands for Network Time Protocol, which is used to connect to a different server 38 00:02:32,820 --> 00:02:37,960 over the internet to fetch the time accurately. This isn't commonly used on home PCs though, 39 00:02:37,960 --> 00:02:42,260 so that little battery on your motherboard is still quite important. In fact, if you remove it, 40 00:02:42,260 --> 00:02:46,920 you'll probably find that your BIOS settings will still reset, just like they did in the old days. 41 00:02:46,920 --> 00:02:51,520 I'm assuming because of tradition. Just kidding, that was a joke, but actually not really. 42 00:02:51,520 --> 00:02:56,240 Because people were so used to removing the battery as a means of resetting the BIOS for so long, 43 00:02:56,240 --> 00:02:59,240 most PC manufacturers simply kept this functionality 44 00:02:59,240 --> 00:03:03,960 in place as an easy way to clear settings. Of course, there are a good number of motherboards out there 45 00:03:03,960 --> 00:03:08,320 that feature a clear CMOS button, either on the board itself or on the rear IO, 46 00:03:08,320 --> 00:03:13,040 that will also reset your BIOS settings, though its name is technically a misnomer now. 47 00:03:13,040 --> 00:03:17,560 The reason they kept the terminology was again, because folks have just been so used to using CMOS 48 00:03:17,560 --> 00:03:20,680 as a synonym for BIOS that the name just stuck. 49 00:03:20,680 --> 00:03:24,680 And although all this may be a little confusing, the good news is that the CMOS battery 50 00:03:24,680 --> 00:03:27,960 isn't something you have to worry about very often. They typically last for years 51 00:03:27,960 --> 00:03:32,360 before they might need to be replaced, but you might wanna have a copy of your BIOS settings 52 00:03:32,360 --> 00:03:38,960 saved somewhere anyways, especially if you're the type of person to spend hours getting your RAM timings just right. 53 00:03:38,960 --> 00:03:42,840 You can't get that time back, but you might as well have your BIOS settings. 54 00:03:42,840 --> 00:03:46,640 But I appreciate you spending the time that you can never get back to watch this video. 55 00:03:46,640 --> 00:03:50,200 Hey, like the video if you liked it, dislike it if you dislike it. Check out our other videos 56 00:03:50,200 --> 00:03:55,480 and comment below with video suggestions. Don't forget to subscribe and follow to Techquickie, 57 00:03:55,480 --> 00:03:58,040 which is this channel right here.