Continuing in a series of explanations of computer hardware, let’s look at motherboards! How do you tell motherboards apart? If you can hook all your hardware up to two motherboards, which one is better?

BASIC STUFF: THE MOTHERBOARD AS CONNECTIVE TISSUE

The most important thing about the motherboard is that it connects all the individual parts of your computer. The motherboard contains the wires that let data flow between CPU, GPU, RAM, HDD, your keyboard and mouse, etc. — it is the spinal cord of your computer.

When you’re buying a motherboard, the most important spec is the “socket type” of CPU that it supports. “Socket type” refers to the physical connection between the pins on the CPU and the sockets on the motherboard. A processor built for one socket type will physically not fit in a motherboard built to accept another socket type. Intel and AMD processors use different socket types. Furthermore, both companies create new socket types every few years, requiring motherboard upgrades to use the (presumably better) CPUs built to the new socket type. So, buying an Intel LGA 1155 socket-type motherboard locks you out of all AMD chips and all Intel chips older or newer than that socket type. Chances are, if you have to buy a new motherboard, it’s because new CPUs can’t work in your old one.

Number and type of expansion slots is the next most important thing. You may want to use many sticks of RAM or 2+ graphics cards, and some motherboards can’t support that. Furthermore, RAM, USB ports, hard drives, and GPUs are also built to standards that evolve over time. Although these standards don’t change as frequently as CPU chipsets (and Intel and AMD socket motherboards both support the same standards for all these things), you’ve still got to make sure that they’re supported.

Most desktop motherboards will support 240-pin DDR3 RAM, but different motherboards support different speeds of RAM (this is the 1066, 1333, 1600, etc.) Higher is better. Make sure to look up the number of memory slots too — Fewer slots of RAM isn’t a dealbreaker, but more slots is better. For instance, you can save money by buying 16GB of RAM as 4x 4GB sticks instead of 2x 8GB sticks.

You’ll also see PCI (“Peripheral Component Interconnect”) expansion slots listed on motherboard specs. These slots are where you insert specialized hardware as needed — audio cards, network cards, video cards, and even some SSDs use PCI slots. There’s multiple standards of PCI, and again, bigger numbers (and the word “express”) is better. Stuff that can afford to be slow, such as network cards, only need PCI. Nice sound cards and PCI-based SSDs will want PCI Express, which allows faster data transfer. Video cards are the only things that really need PCI Express 2.0+, since they transfer absurd amounts of data.

There’s other considerations like form factor (desktops are ATX), built-in audio/network/video cards (use expansion-slot cards if you can, but these get the job done), and HDD connectors (almost everything runs on SATA 6gb/s nowadays). These are all boring and don’t change very much, so we’re glossing over them.

GETTING FANCIER: THE MOTHERBOARD AS BRAIN

You can go out and buy a usable motherboard just based on the information above, and you’ll be fine. But stopping now is for losers! Motherboards are more than just the wires connecting components.

First, the motherboard contains the BIOS. BIOS stands for “Basic Input/Output System” (pretend like it means “Built-in Operating System” — Neal Stephenson’s idea — because that’s a better name). It’s a super-low-level system where you can see hardware stats and change them. This is the settings screen that you get when you hit F11 or Delete while booting, where you do things like RAID together hard drives, control voltage/timings, and specify to boot off HDD or CD. Honestly, 95% of motherboard manufacturers’ BIOS utilities feature 95% of the things you care about, so it’s not a factor in your motherboard purchase.

Less visibly, but more importantly, the motherboard contains the Northbridge and Southbridge chips. These chips manage communication between each part of your computer, and they are vital. The Northbridge manages access to high-importance / high-data-transfer-rate parts of the computer, like RAM and video cards in PCIe slots (also, the Northbridge is being phased out of existence, as more system-on-chips wrap the Northbridge into the CPU). Southbridges manage access to lower-importance / lower-data-transfer-rate peripherals in PCI, USB, or SATA slots (i.e. audio cards, keyboards/mice, slow hard drives).

Since a ton of data transfers happen that don’t involve the CPU at all (RAM <-> video card; USB stick <-> printer), and the CPU is usually held back by memory transfer speed anyway, the Northbridge and Southbridge play an important role: not slowing the CPU down by making it a middleman in these transfers. A good Northbridge and Southbridge are the caretakers that make your entire machine flow smoothly.

What’s the difference between a good and bridge Southbridge? the Intel Z77 chipset can communicate at 5GB/s with 8 PCIe 2.0 slots and 6GB/s with 6 SATA ports. However, Intel’s H61 can only handle 6 PCIe 2.0 slots, and only 4 SATA ports at 3GB/s — even if you installed a USB 3.0 card on a H61 motherboard, it wouldn’t run at full speed. (In general, ‘H’ means ‘budget’ and ‘Z’ means ‘performant’ for Intel).

These chips are the things that make one motherboard more expensive than another with the same slots — and although a budget Northbridge/Southbridge can hold you if you aren’t pushing the boundaries of your CPU, certain PC builds will see stunning increases by swapping out the motherboard alone.