WEBVTT 00:00:00.000 --> 00:00:05.040 If you own a desktop computer, the number of USB ports at your disposal might be an embarrassment 00:00:05.040 --> 00:00:10.800 of riches. Even mid- to low-range machines can offer more USB than you could possibly know what 00:00:10.800 --> 00:00:16.720 to do with. But is it actually a good idea to use them all at once? Here's the deal. You know how 00:00:16.720 --> 00:00:22.400 the makers of USB products like to loudly yell about how blazingly fast they are? Well, it's 00:00:22.400 --> 00:00:27.360 fairly common knowledge in the tech world that those advertised numbers are theoretical 00:00:27.360 --> 00:00:34.320 maximums that you probably won't see in reality. And using multiple USB ports at once can actually 00:00:34.320 --> 00:00:41.840 cut into these speeds even further due to a separate effect. You see, your computer's USB ports are 00:00:41.840 --> 00:00:48.320 connected to controller chips inside the system, and a single USB controller can only handle so 00:00:48.320 --> 00:00:53.840 much traffic. So let's say you have two USB 3 ports on the front of your computer connected to a 00:00:53.840 --> 00:00:59.360 header on the motherboard that utilizes one controller. You can get the full five gigabits 00:00:59.360 --> 00:01:05.200 per second if you're just plugging one flash drive into those ports. But if you're using both, 00:01:05.200 --> 00:01:10.960 then those two drives actually have to share that five gigabits of bandwidth. So if you're 00:01:10.960 --> 00:01:17.120 moving data on both ports simultaneously, the theoretical maximum speed per port will be cut 00:01:17.440 --> 00:01:24.000 in half. And this isn't just true for front panel inputs. Oftentimes, the ports on the back of your 00:01:24.000 --> 00:01:30.080 PC, which don't even use a header cable, are susceptible to the same problem. It just isn't 00:01:30.080 --> 00:01:35.040 all that common for a port to have its own dedicated controller utilized by nothing else. 00:01:35.760 --> 00:01:42.560 So why not one controller per USB port? Well, think about how most people use their USB ports. 00:01:42.640 --> 00:01:47.280 You'll have a flash drive to transfer data every now and again, but your other ports are 00:01:47.280 --> 00:01:53.520 probably being pressed into service for your keyboard, mouse, headset, or novelty glitter lamp. 00:01:53.520 --> 00:01:57.840 And none of those things requires very much bandwidth. Given then that the vast majority 00:01:57.840 --> 00:02:03.440 of users aren't constantly blasting data down multiple USB ports at once, there just isn't 00:02:03.440 --> 00:02:10.080 much reason to build a bunch of controllers onto a typical motherboard. But most systems do have 00:02:10.160 --> 00:02:15.280 more than one USB controller. If you go into Windows Device Manager, you'll typically see 00:02:15.280 --> 00:02:21.040 multiple devices that are labeled USB host controller. So it's not like you have eight or 00:02:21.040 --> 00:02:28.000 12 ports that are all sharing one pipe. However, do keep in mind the limits of a single controller 00:02:28.000 --> 00:02:33.680 if you're doing something heavy, like editing video and constantly backing up footage or 00:02:33.680 --> 00:02:39.120 using a VR headset with your PC. In fact, Oculus officially recommends connecting no 00:02:39.120 --> 00:02:44.880 more than two of their sensors to a single USB controller due to how much data needs to be 00:02:44.880 --> 00:02:49.840 processed for a smooth VR experience. This is not just due to possible bandwidth issues, 00:02:49.840 --> 00:02:53.840 but also due to the logic of the controllers themselves becoming overloaded. 00:02:54.480 --> 00:02:59.440 And keep in mind that a similar concept applies to the way that USB handles electrical power. 00:02:59.440 --> 00:03:03.040 If you're trying to charge or power multiple devices from your computer, 00:03:03.040 --> 00:03:08.240 each device won't get the full amount of power if many of them are connected to the same internal 00:03:08.240 --> 00:03:13.920 hub. So you could see slower operation if you're using an older mechanical external hard drive or 00:03:13.920 --> 00:03:18.240 a couple of those novelty fans to cool you down because you spent all your money on a graphics 00:03:18.240 --> 00:03:23.120 card and didn't have enough leftover for an air conditioner. So if you have a lot of USB devices 00:03:23.120 --> 00:03:28.080 that you need to use at once, think carefully about how much data they'll be moving and also 00:03:28.080 --> 00:03:33.440 do some digging to see how many host controllers your computer comes with. I know that, yes, 00:03:33.440 --> 00:03:40.240 theoretically you can connect 127 devices to a single USB controller, but I wouldn't recommend 00:03:40.240 --> 00:03:45.040 trying that unless you have a very good reason. Just like I'd recommend subscribing, 00:03:45.040 --> 00:03:48.480 because you have a great reason. These videos are great. Get subscribed.