After you have decided the best CPU and GPU combination you must choose your Motherboard. This is the main board that connects every other component in your system together, and is crucial that it be compatible with every component in your build. This may sound scary, but most modern components are built to some standard, so its more likely than not everything will work. But there is still a lot to take into consideration with your choosing of a motherboard, so lets get started
Key Motherboard Factors:
1. Northbridge and Southbridge
2. CPU Socket type
3. Form Factor
4. Memory Standard
5. Expansion Slots
6. Onboard Video
7. Onboard Audio
8. Storage Device Connectivity
9. Onboard Local Area Network
10. Universal Serial Bus
11. Other Features
Northbridge and Southbridge
These are the two "bridges" that connect everything to your Central Processing Unit. The Northbridge handles the Graphics Card and Monitor connection, and the Southbridge connects everything else: storage devices, USB, Audio, LAN, etc. These are crucial as different northbridges offer different bandwidth and features. Remember in the GPU article I mentioned how the PCI-e has a 16x lane bandwidth? But in some mobos its only 8x when you're in SLI or Crossfire? That is dependant on the Northbridge, some of the high end boards can actually run 16x/16x in SLI and Crossfire, widening the bandwitdth. This is crucial for a gaming rig, as obviously it connects one's GPU, CPU, and the Monitor. The southbridge can be equally crucial, as the newer SB750 southbridges found in AMD boards offer what AMD calls Advanced Clock Calibration for more efficient overclocking, which will be covered later.
Here is a map of the newer AMD 790GX Northbridge and SB750 Southbridge
CPU Socket type
Must have the same socket on the motherboard as does your CPU, otherwise it wont fit. For example, an Intel LGA 775 socket CPU will NOT fit in an AMD AM2+ socket motherboard or even in an Intel LGA 1366 motherboard. If you have an Intel CPU with an LGA 775 socket you MUST get a motherboard with an LGA 775 socket.
This next paragraph may get confusing so stick with me. Sometimes AMD or Intel will release a new CPU with a new socket, but will design them to be compatible with an older socket motherboard. This is great news for people who just want a CPU upgrade without upgrading their motherboard too. An example of this is the new AMD CPUs with an AM3 socket can fit into a motherboard with the older AM2+ socket. This is not the case with every CPU that becomes available so you will have to do some research to ensure compatibility. (As mentioned before I will go over the current PC technology including which CPUs are available and what will be compatible with what).
This is crucial to ensure your motherboard will fit into your Computer Case. Most motherboards have an ATX form factor as do most cases. Another common form is the mATX, or micro ATX form factor. Obviously it is much smaller and designed to fit into smaller cases. These typically do not have the same performance as the full ATX boards do because they have to sacrifice some to make them smaller.
The memory standard will determine what type of memory your system will use. Memory will be covered in the next article so I won't go over it at the moment.
These are the slots where you will install your graphics card, so it is important to have the right slots for your type of GPU, and enough slots if you want to add extra GPUs for an SLI or Crossfire set up.
These slots can also be used to add other expansion cards such as network or USB cards as mentioned earlier. If you are going to make your PC wireless then you will most likely need a PCI wireless expansion card.
Some motherboards come with an actual GPU integrated. These are typically used for laptops, business computers, or for computers where intense graphics is not important. Some platforms, however, can benefit gaming, not performance but energy efficiency. Some boards can actually tune down the Graphics Card and only use the onboard GPU when the user is just on the desktop or using programs that don’t require enhanced graphics. This ultimately cuts down on power consumption and your electric bill.
Most modern motherboards have very good quality onboard audio. In the past, the onboard audio wasn't very effective, and ultimately the CPU had to process all of the audio for the video game, thus hurting performance. The best solution was adding a Sound Card to an expansion slot, taking the load off of the CPU. However, because of the how easy it is to process audio and how powerful CPUs are this isn't a problem. Most system builders prefer to save their money and simply use the onboard audio, though there are a variety of Sound Cards available to deliver improved audio quality.
Storage Device Connectivity
Basically what you will use to connect your Hard Drive or Solid State disk to your motherboard. Once again it is vital to ensure you have the same connections on your mobo that your particular hard drive uses. Most modern motherboards carry both the latest SATA II connections and the older IDE connections (SATA and IDE will be covered in the hard drive article).
Onboard Local Area Network
Most, if not all, motherboards come equipped with a 10/100/1000mbps LAN (local area network) port so you can connect to your Router or hub and enjoy the fruits of the magical super fast broadband internet and internet gaming. 10/100/1000mbps means that it is compatible with a Router or Hub with the same connectivity. Mbps means Megabytes per second, so if you have two computers on the same local area network that have 10/100/1000mbps via onboard LAN and are connected to a Hub or Router that has 1000mbps LAN, then you can transfer 1GB of information in one second. That’s fast.
However it is important to note most broadband ISPs (Internet Service Providers) only offer 10 to 20mbps, so the 1000mbps LAN will bottleneck down to 10 or 20mbps when you're on the internet.
Universal Serial Bus or USB
Everybody and their mother should know what USB is: its how you connect your Ipod to your computer! Every modern motherboard is equipped with with USB 2.0, and when USB 3.0 becomes available you'll be able to upgrade via an expansion slot.
Some motherboards offer some energy efficient technology to lower power consumption when the system isn't at full power load. Others, like the AMD boards that have and SB750 Southbridge, have more advanced features for overclocking. Generally good information to research when picking your mobo.