The terms Northbridge and Southbridge are related to the Intel motherboards only. It is a technology that connects the processor or CPU (central processing unit) to the motherboard to access specific functions. The CPU is the brain of any computer system that controls and manages the other hardware.
This hardware is usually either installed right on the motherboard or using the data cables on the motherboard. CPU on an Intel motherboard controls all of them and other functionalities of your motherboard using these bridges called Northbridge and Southbridge. Let’s discuss this very topic in a bit more detail.
Do Modern Motherboards have Northbridge and Southbridge?
On modern Intel motherboards, the basic functions of the northbridge are integrated into the CPU. In contrast, the PCH (platform controller hub) has a design to combine the other functions of northbridge and southbridge. In 2009, Intel introduced it in 5 Series motherboards.
Intel motherboards do have the northbridge and southbridge. Intel motherboards add these bridges to their motherboards. Northbridge connects the CPU or processor to the most important functions, while Southbridge connects the CPU to less important tasks, but both are essential for the motherboard.
The northbridge in an Intel motherboard controls or manages the communication among the CPU and other hardware such as RAMs, AGP, or PCIe slots (GPU or graphics cards). You can say that northbridge is responsible for the most basic and essential communication management in an Intel motherboard.
It is because it is the responsibility of the CPU to execute the apps and software. And for this, it needs them to be loaded in the RAMs, so it can fetch, decode, and execute them. For this, it uses the northbridge for communicating with the RAM to store data and instructions before and after processing.
The CPU also uses northbridge to store the data in the RAM on the storage media such as SSD (solid state drive), HDD (hard disk drive), USB flash drive, etc. During this, the computer processor generates the addresses for storing the data on certain available locations on a storage media.
PCIe slots are the slots that connect the graphics cards to the motherboard. The northbridge establishes communication between the CPU and GPU to work on a certain graphical problem as a team. For example, when you run a game on your computer, the CPU starts it, and the GPU helps you play it.
On the other hand, we have Southbridge on the Intel motherboards. Some northbridges on the Intel motherboards contain integrated video controllers, also known as GMCH (Graphics and Memory Controller Hub). These are the built-in or onboard graphics cards on the intel motherboards for calculating and displaying graphics.
The input and output functions are also the responsibility of southbridge. This bridging technology establishes the path and communication between the input-output devices and your computer system. These devices include a keyboard, mouse, display monitors, microphone, camera, speakers, etc.
Northbridge is an IC (integrated circuit chip) on Intel’s motherboards on the north side. Similarly, the southbridge is located in the south of the Intel motherboards. It is directed toward the FSB (Front Side Bus), also known as MCH (memory controller hub) or host bridge.
The southbridge is located south of the PCI (peripheral component interconnect) Bus. It controls the input-output functions in an Intel motherboard. The southbridge cannot work without the northbridge because it connects it to the CPU. This way, the CPU can send control signals to the I/O devices.
There are 127 input-output devices that we can connect to a computer system using USB ports. And without the southbridge in Intel’s motherboards, this task was impossible. All the I/O devices connected to a PC using the USB hubs use this bridge to transfer their data and instructions.
Hence, both of the bridges, the northbridge, and the southbridge, are necessary for making a computer system functional. It is because they are the only way all the hardware on the motherboard or the devices connected to a computer can communicate. The latest Intel bridges are very fast.
Difference Between Northbridge and Southbridge
For your ease, we have created a table below to differentiate between northbridge and southbridge. But do remember that these terms are related to the Intel motherboards only. We hope it will be very helpful, especially when you are a computer student:
| Northbridge | Southbridge |
| The physical location of the northbridge IC chip is in the north of the Intel motherboard. | The southbridge is in the south of the PCI slot of the Intel motherboard. |
| It is also called Host Bridge or Memory Controller Hub (MCH). | The other name for the southbridge is I/O Controller HUB. |
| Northbridge is directly connected to the CPU, RAM, and PCIe slots. | Northbridge connects both the CPU and southbridge. |
| It establishes and manages the communication among the CPU, RAM, and graphics card. | It establishes and controls the input-output functions using the I/O devices such as the keyboard, mouse, monitor, mic, etc. |
| Northbridge is way faster than southbridge. | The southbridge communication speed is comparatively slower. |
| It is located near the CPU or processor for faster and easier access. | It is present near the PCI slots or buses. |
| The northbridge is the only communication between the main memory or RAM and the processor or CPU. | The southbridge is the only method for controlling and establishing the input-output functions. |
| It connects faster Buses like AGP (Accelerated Graphics Port) Bus. | It connects the slower ISA (Industrial Standard Architecture) Buses. |
| The size of the northbridge IC chip is bigger. | The size of the southbridge is comparatively smaller. |
| It connects hardware like RAMs, CPU, GPU, etc. | It connects the devices connected to the USB (universal serial bus) hubs or PCI slots. |
Features of Northbridge
The northbridge on an Intel motherboard establishes the communication with the CPU or processor via Front Side Bus (FSB). This bridge is responsible for the communication between the CPU and the RAMs on the motherboard. When executing an app or software, the CPU loads its instructions and data in the RAM or main memory.
Northbridge is the only path through which this process is carried out. After processing the results, the CPU or processor temporarily stores the data, instructions, and addresses in the RAM using the same bridge. Even though the control signals for reading, writing, or clearing the main memory use the northbridge.
The southbridge depends on the northbridge for communicating with the CPU. Hence, some of the I/O functions performed using the southbridge depend on the northbridge. For controlling the display monitors, the north bridge provides a way to the AGP and PCIe ports or slots on the Intel motherboard.
Pros and Cons of Northbridge
There is no disadvantage of the northbridge that we know so far, but there are plenty of advantages. It is the only communication path among the CPU, RAMs, AGP, or PCIe slots. Not only this, but it is the fastest communication medium among the latter hardware and interfaces, as the CPU is the fastest hardware.
As a result, all the credit for the fast speed of Intel motherboards goes to the northbridge because the processor or CPU controls different hardware using it. Not only that, but the northbridge also connects the southbridge to the CPU. Hence, it allows the processor in an Intel computer system to control the I/O devices.
Features of Southbridge
Southbridge is the only pathway that provides communication between a computer user and the computer itself. It does this by making the I/O devices functional as it controls their working. We all know that it is very difficult to use a computer system without a mouse and a keyboard.
Not only this, but it also makes the other I/O devices like microphones and speakers functional. And without them, a computer will be nonresponsive for nearly all of us. In addition, southbridge makes the USB hubs available for us to connect USB-compatible devices from flash drives to memory cards.
Pros and Cons of Southbridge
The main advantage of the southbridge is that it establishes a communication path for the input-output devices such as keyboard, mouse, microphone, speakers, etc. Without the first two I/O devices, it is impossible to use a computer system; hence it is the greatest advantage of the southbridge on an Intel motherboard.
The only con of the south bridge is its slower speed than the northbridge. It is because the input-output devices operate on a way slower frequency than the RAMs or CPU. But if you allow the I/O devices to communicate directly to the CPU, they will burn out into ashes because of the high frequency.
Moreover, the southbridge supports the ACPI or Advanced Configuration and Power Interface. This feature allows the computer system to go into sleep mode or hibernate mode. Not only that, but it also reduces the power consumption of the computer system.
Conclusion
To sum it up, the northbridge and southbridge are vital components of an Intel motherboard. The northbridge doesn’t have any disadvantages but provides the fastest communication path to the CPU and RAMs. On the other hand, the southbridge establishes a way for I/O devices like keyboards, mice, microphones, speakers, and other USB devices to communicate with the CPU.
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