Motherboard Chipsets – CompTIA A+ 220-801: 1.2

| August 27, 2012


The PC motherboard is a mix of hardware, and there are many different chipsets and bus connections that make up our modern computers. In this video, you’ll learn about different motherboard chipsets and how to easily recognize motherboard components.

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Review Quiz: Motherboard Chipsets

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Our modern computers are incredibly complex. There’s so much happening on the motherboard itself. We have a CPU that’s communicating constantly to the memory modules on these devices. We have high speed video output that has its own series of processors. They are all types of peripherals and USB connections going into the motherboard, and it is managing all of this with the chipsets that are on the device.

You’ll sometimes hear a motherboard referred to as a mobo. You’ll see a written that way if you’re purchasing a motherboard. It’s often referred that way on a website. And there’s so many different kinds of motherboards that you’ll come across. You’ve got different motherboard types depending on what you’re trying to accomplish.

You’ll notice the motherboards have also changed through the years. We’ve improved chipsets, the bus speeds have gotten much faster, the methods for cooling these motherboards have gotten a lot easier than they used to be. So as we use different types of motherboards, you’ll find there are a lot of different options you’ll be able to choose from.

When you first look at a motherboard, it looks pretty chaotic. There are all kinds of different components on this, all kinds of different chips that you could see. There are dip switches involved. There’s places where CPUs might go. If you’re looking at it for the very first time, it doesn’t look like any of this works together, but in fact, the motherboard is designed very specifically so that all of these different components can work with each other. Let’s step through the chipset and see exactly how this particular motherboard is laid out logically.

Every motherboard is going to have a CPU on it, and you’ll notice the CPU is connected to something called the northbridge. We’ll talk a little bit more about the northbridge in a moment, but you can see that it’s connected through something called the front side bus. This is one of the largest and fastest buses on your motherboard.

Connecting the northbridge to the CPU is the graphics slot that you might have in your computer, and especially the memory. There’s so much communication that takes place just in that small, little area.

You’ll notice there’s also something called a southbridge. The southbridge is something that connects the other devices on your computer, and all of this works together to make sure that your computer’s able to operate properly.

You may also hear the northbridge referred to as the memory controller hub, and that’s because that’s exactly what it’s doing. It’s managing the communication of the memory to the CPU. It keeps that going very, very quickly. This is a very high speed communication, and because of that, you’ll often plug your video controllers into this as well because it’s designed to be such high speed communication.

You usually don’t see the northbridge just sitting here, right there with no heat sink on top of it and a fan on top of it. This gets very, very hot, so on most a motherboards, you have a heat sink and a fan that might sit right on top of just the northbridge to make sure that it remains cool. I’ve removed it so that we can take a picture of it and see what it looks like under the surface, but if you were ever to look at other pictures of other motherboards, you’re noticing there’s a heat sink right in the middle that’s not on the CPU. That’s probably your northbridge

If the northbridge is handling all of the memory communication and the high speed video, then we need something else to handle all the rest of the communications on your motherboard, and that falls under the southbridge. This is a picture of the southbridge that’s on my motherboard. It may or may not have a heat sink associated with it. It’s not going quite as fast as the northbridge is because it’s handling some of the slower speeds, like your PCI or your PCI express interface slots.

There might be other peripherals that it’s managing, like USB connections, the ethernet connection that’s plugged into your motherboard directly. There may be hard drive connections that are being managed by the southbridge. If you have an onboard video controller, you aren’t using a separate adapter card, then your southbridge is probably also managing that communication as well. And lastly, the BIOS of your computer often communicates with or is managed by the southbridge on your motherboard.

Now that we know what a northbridge and a southbridge does, let’s look at this again. We can see the northbridge handling the memory and the high speed graphics communication. There’s our southbridge, and it’s handling onboard graphics, our flash BIOS, our interfaces to our serial ports and parallel ports and USB ports, and we have our slower adapter slots off the southbridge as well.

Well, seeing that in a picture, in a logical diagram, is one thing, but let’s go back to the picture of our motherboard, and let’s see if we can find where all of these different devices plug in. If we start looking at the motherboard, we’ll see right at the top, we have two CPUs on this particular model of this motherboard. Your motherboard probably only has a single CPU if it’s not being used as a server. So we know the CPUs are here, and we also know the memory– we can very easily see the memory module connectors right there on the motherboard.

We know that the northbridge manages the communication between the CPU and the memory, so as we look at this motherboard, you’ll notice right in the middle of those is the memory controller hub, is that northbridge communication. And that handles really this top half of the motherboard itself.

If we move our view to the bottom of the motherboard, you’ll notice there are a lot of different chips that are on here. We certainly have our PCI slots that are here. So if you’re having adapter slots, they might be down right here. In this lower part, you’ll see the onboard graphics controller chip on this motherboard is very close by, along with the flash BIOS and what we call a super I/O. There’s a separate chip that’s on the motherboard that handles communication to some of these other type of ports and other type of peripherals.

So right in the middle of all of those is the southbridge. It is handling communication to all of these. Notice that it is very geographically oriented. You don’t have the southbridge way up on the other side of the motherboard. It’s going to be somewhere close to all of the different devices that it manages. And in the same way, the northbridge is always going to be very close to the CPU and the memory.

As we look at our motherboards, and we think about the logical layout of the northbridge and the southbridge, what you’ll find is through the years things have changed a bit. We’ve been able to make our processors much more efficient. We’ve been able to add additional capabilities to our processors. And some of the things that were separate chips like our northbridge, or separate interfaces like our video that was built into our system that connected to our southbridge, we’re now putting right onto the CPU, because now our CPUs are much more capable.

If you were to look, in fact, at some of the latest types of CPUs like the Sandy Bridge models from Intel, you’ll notice that it has processor cores on it. There’s a memory controller I/O, so this is where our northbridge used to be. We don’t have to have a separate northbridge chip anymore. That memory controller and the I/O to the memory is right there on the CPU. And notice that the processor that we used to have, the built-in graphics chip that was a separate chip on our motherboard that often connected to the southbridge, now also included onto the CPU of our system.

So although these are now integrated in, and they’re a little bit different than they’ve been in the past, it’s still useful to at least think of the functionality of the northbridge and the southbridge from a logical perspective, but keep in mind that a number of those capabilities may be embedded right on the CPU itself.

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Category: CompTIA A+ 220-801

Comments (1)

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  1. Great tutorial, the best explanation of it all I’ve seen. It’s so much easier to have someone explain it to me rather than reading it. Thank you very much! 🙂

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