Wondering what all those chips, slots and sockets do? Read on.

Don’t be afraid of it. Don’t ignore it. The motherboard is one of the most crucial parts of your PC. If the CPU is the brains of the outfit, then the motherboard acts a little like the skeleton and nervous system, supporting all the other components in your PC and ensuring that they can all talk to each other. This is why the motherboard is so important, and why Alpha Beta PC works hard to pick the perfect one for each system. A good motherboard helps maximise performance and gives your PC scope to evolve. Compromise on your motherboard and it will limit what you can do, and put the brakes on when you least expect it.

So, what are the vital elements of the motherboard, and how do they impact how you use your PC? Let’s take a look with one of Alpha Beta PC’s most popular motherboards, the Gigabyte Z690 UD.

1. The CPU Socket: This is where your Intel or AMD processor sits, with the hundreds of pins or connectors on the bottom of the CPU package connecting to the matching holes or contacts in the socket, so that the chip receives the power it needs to work and data can stream to and from the CPU to the other core components. Right now, mainstream AMD processors use the AM4 socket while mainstream Intel processors use Socket 1700, just like the one here. However, the next generation of AMD processors – the Ryzen 7000 series – will use a new socket, AM5.

  1. The DIMM slots: These two to six slots house the RAM modules, which slide in, in one direction only lengthways and click down into restraining clips at either end. Depending on the CPU and motherboard, the RAM will be separated into two to four channels, each assigned their own memory controller on the CPU. The DIMM slots are usually colour coded to help you assign each module or pair of modules into a different channel, to maximise the memory bandwidth between the CPU and each DIMM. 

Your motherboard will usually support one type of RAM – either DDR4 or DDR5 – at speeds set by the Northbridge in the CPU. The Z690 UD supports DDR5 RAM at speeds of up to 6000MHz, where the CPU supports it.

  1. Expansion Slots: Each motherboard will have three or more PCI express expansion slots, with the spec varying depending on how many PCIe lanes it provides for communication with the CPU or with the motherboard’s Southbridge chip. The shortest slots will be single-lane or PCIe x1 slots, with the others four-lane (PCIe x4), eight-lane (PCIe x8) or sixteen-lane (PCIe x16). The more lanes, the more bandwidth for data flowing through the slot, which is why the x16 PCIe slots are reserved for bandwidth-hungry graphics cards, while the PCIe x1 slots are only used by less demanding audio or wireless networking cards.

Different motherboards will give you different configurations of expansion slots, depending on their size and price and on how many PCIe lanes the Southbridge chip can support. Here the Z690 UD gives us one x16, two x4 and two x1 slots. One reason to buy a full-sized ATX case and a larger ATX format motherboard is that you’ll get more expansion slots to work with.

4. External ports and internal headers: The external ports go directly through the backplate of your PC case to give you a range of USB Type-A, USB Type-C, HDMI, Ethernet and audio inputs and outputs. However, your motherboard will also have internal headers designed to connect to any USB or audio ports on the front, top or side of your PC case. It’s worth checking through these carefully. While the Southbridge chip will usually define which ports and how many ports your PC includes, cheaper motherboards will offer a more limited selection, or even not support the fastest USB standards. Sorry. It’s a whole other article explaining those!

5. SATA Connectors: These connect using SATA cables to HDDs and 2.5in SATA SSDs. The interface will be limited to the six gigabit per second maximum speed of SATA III, which is approximately 13x slower than the eight gigabyte per second maximum of the PCIe 4.0 M2 slots we’re going to get to in a minute. However, the drives themselves aren’t any faster, so they’re mostly used these days for mass storage of media and game files.

6. Fan connectors: These provide power and control connectivity for system fans, CPU fans and other coolers in the system. Basic motherboards may only have the bare minimum of headers for a system fan or two and a CPU fan, while high-end motherboards will have a wider range to cover and control different system fans, adjusting their speed according to the temperature of the CPU and any other core components.

7. Power connectors: Modern motherboards will have a 24-pin connector to bring power in from the power supply, along with a specific 4-pin or 8-pin connector that routes power through to the CPU. Other components, like the graphics card or hard drives, will take additional power direct from your power supply.

8. M2 Slots: These are designed to house M2 SSDs or, occasionally, wireless networking cards. Most will have four lanes of connectivity to the Southbridge chip, though some motherboards will cheapskate by only offering two lanes on the secondary M2 slot, meaning you won’t get full performance with the fastest drives. The actual PCIe standard of the slot will be defined by the CPU and Southbridge chip. We’ll get to why this counts in a minute.

9. BIOS chip: The BIOS (Basic Input Output System) is the firmware of your motherboard, controlling all the most basic operations of your PC. It also checks the health and presence of your core components, and feeds you error messages through beeps or LEDs on the motherboard should something go wrong. You may need to update it for new processors or to fix issues, but don’t worry: this will be a simple software process rather than anything physical on the motherboard itself.

  1. Motherboard controller: This controls motherboard operations and houses the Southbridge chip. To explain, motherboards used to have two controller chips: a Northbridge to handle communications between the CPU, the GPU and RAM, and a Southbridge with a high-bandwidth connection to the Northbridge, plus connections to all the ports and storage on the system. Now the Northbridge is part of the CPU.

Together, the CPU and controller chip will define some aspects of your PC, like the maximum speed of RAM that your PC will support or the PCIe standard supported by the expansion slots and M2 slots, which today should be PCIe 4.0. When it comes to M2 drives the Z690 UD only goes as far as PCIe 4.0 for drives with speeds of up to 8GB/sec. We’ll only see PCIe 5.0 M2 drives when AMD releases its Socket AM5 motherboards and CPUs.

The Southbridge will also define which standards any ports on your PC support, such as USB 3.2 Gen 2, USB 3.2 Gen 2×2 or Thunderbolt 3 or 4, though certain motherboards may have their own dedicated USB or network controller chips onboard. Certain overclocking features may also be restricted to higher-end chipsets.

Generally speaking, each new line of Intel or AMD processors will come accompanied by a new line of motherboard chipsets. Right now with Intel, you’re looking at the H610 as the mainstream, value option, with H670 and B660 having more enthusiast features, and the best features reserved for the high-end Z690 chipset, which you can’t actually see here as it’s concealed under a massive hood and heatsink.

With AMD, the equivalents are the B550 for the mainstream and the X570 as the high-end choice. More than anything else, your choice of chipset will set your budget for your motherboard, so think carefully about whether you want to compromise on certain features and have more to spend elsewhere, or splash out on an enthusiast motherboard as a platform for future upgrades.

If you’re still not sure about what motherboard to base your new PC on, fear not, just drop a line to the experts at Alpha Beta PC and they’ll help you make the right choice for you.