Motherboard Northbridge vs Southbridge – Compared and Explained

Last Updated on November 6, 2020

The motherboard is a complex piece of technology that has served as the backbone for computers for decades now. It has provided us with the means to connect different components of a computer and let those share and access data.

The motherboard makes this possible by utilizing complex Integrated Circuits (ICs) which allow all the components to be connected.

In this article we compared northbridge vs southbridge. This were used in the older motherboard architectures and more or less obsolete now.

Through these ICs, the motherboard got a “bridge” that let the CPU connect to each part of the computer; the memory, the storage, connected external devices as well as cards that may be installed on PCIe connectors.


What is a Chipset?

northbridge vs southbridge

Through the chipset, the motherboard is connected to the CPU. It is this link that allows us to utilize all the services of the CPU. A computer’s chipset is made up of the Northbridge and the Southbridge.

What is the Northbridge?

The Northbridge is one of the ICs that a computer utilizes to connect to some devices on a computer. It is also referred to as the PCI/AGP Controller (PAC).

It offers a bridge for devices to communicate directly with the processor and through it, the Southbridge is also connected to the processor.

Older computers had more than one IC which together acted as a Northbridge. These were combined into one chip and on more modern Computers, as we will see, this chip is already integrated into the CPU completely.

The Northbridge is located closer to the CPU and memory to offer faster access to these resources.

What is the Southbridge?

Just like the Northbridge, The Southbridge is also an IC on the motherboard that is responsible for connecting devices to the CPU.

It is aptly named because of its position south of the PCI bus and its main purpose is to connect components such as the sound card and other I/O devices to the motherboard.

The Southbridge is usually smaller than the Northbridge and much farther from the CPU and memory.

Also Read: Best ATX Motherboards for Gaming

Functions of the Northbridge vs Southbridge

Source: Gigabyte

These two ICs make up the chipset that is concerned with ensuring data flows between the devices connected to the motherboard and the CPU.

However, this is a general function and on a deeper level, these two ICs play very different roles.

Functions of the Northbridge

The Northbridge is used to connect the CPU to high-speed components, components that are very time-sensitive and need to send and receive data from the CPU with very little latency.

One such component is the RAM. It needs to be constantly updated with the data and resources that the CPU needs and were it to slow down then the computer itself would be disadvantaged.

Since it links the main memory directly with the CPU, the Northbridge is also known as the Memory Controller Hub or MCH.

This IC is also used to connect the AGP (Accelerated Graphics Port) to the CPU. This port lets you attach a video card to the motherboard and can help in rendering views on the screen much faster and more efficiently than the CPU can do on its own.

The Northbridge can also play a role in determining the kind of processor and memory you can use on your computer.

The chipset is built to work with very specific devices and this can be a telltale signal of the kind of mods you can do on your board.

The Northbridge routes data between the CPU and the main memory. It helps that this chip can also be overclocked to perform operations faster and hence improve the overall speed of your computer. You can change the Northbridge multiplier in the Bios where this feature is unlocked.

Also Read: Best Motherboards for VR

Functions of the Southbridge

Also known as the I/O Controller Hub (ICH) on some Intel systems, the Southbridge is used for the much slower components that do not necessarily need very high-speed connections to the CPU.

It links devices such as the SATA controllers, built-in audio controllers, Ethernet, PCI slots and USB controllers to the motherboard. Many of the computer’s I/O devices are connected through the Southbridge.

The Southbridge itself isn’t connected directly to the CPU either. It has to go through the Northbridge to get to the CPU hence you will find that it’s usually smaller than the Northbridge. On Intel systems, the link between the Northbridge and the Southbridge is created over the DMI interface.

The Southbridge is also used to connect to the Super I/O. The Super I/O is a chip that has been used to connect over many decades to connect slower components to the motherboard and after it is commonly used on modern computers to support legacy devices.

Differences between Northbridge vs Southbridge

The Northbridge and the Southbridge connect different classes of devices to the motherboard. While the Northbridge connects high-speed devices to the CPU, the Southbridge takes care of connecting the slower I/O devices.

The Northbridge handles the main memory of the device and needs to be fast enough to allow high-speed data exchanges.

In some systems, the Northbridge is built directly into the CPU itself to limit the latency between computer memory and the CPU.

This has also played a huge role in reducing the size of the motherboard construction and reducing manufacturing costs.


The Northbridge and the Southbridge make up the chipset that acts as the bridge between the motherboard’s components and the CPU.

The Northbridge is located close to the computer and will often have a heatsink. It is used to connect speed-sensitive devices to the CPU as well as to connect the Southbridge to the CPU.

The Southbridge itself is located farther from the CPU and it handles the less speed-sensitive I/O devices.

Its connection to the Northbridge ensures that the devices connected to it can connect to the CPU. The main difference between these two lies in their functions. One is built for speed and the other, not as much.


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I am an engineer with a keen interest and a passion for PC builds and hardware. is essentially the culmination of our enthusiasm towards this subject. We review PC peripherals and hardware, talk about custom builds and informative topics regarding troubleshooting issues, understanding a component better and general tips for DIY PC builders.