CPU Socket Type: This is the socket type for the type of Processor you have chosen. Each type of processor has a unique type of socket type (shape) that will fit into a motherboard. So you must make sure you choose the right motherboard socket type to fit your Processor. For example an AMD Processor with an AM3+ socket type will need a motherboard with an AM3+ socket type.
Chipsets: Will usually be unique to a type of processor and controlsthe communication between the processor and external devices. These will usually refer to the northbridge and southbridge. The northbridge will link the Processor to high en devices such as the main memory and graphics controllers, and the southbridge will connect lower speed peripheral buses. What all of this means to you is that you should simply familiarize yourself with what a specific Chipset is for a specific motherboard. You can do this by choosing the right motherboard for you, then by simply searching Google for that chipset name to familiarize yourself with what that chipset includes. (Do not fret too long over the chipsets as you can usually select a motherboard based on what it includes as described by any decent hardware retailer – but if you want to know more about the motherboard specifics it might be a smart idea to learn more)
Memory: As in how much and what type of memory your motherboard supports. A specific motherboard will support a certain number of memory slots, the numbers of pins your memory must have, the type of memory (ex. DDR3), maximum amount of memory supported (ex. 16GB), and the channel supported (ex. Dual Channel Memory – in this case it is best to install memory in pairs like 2 sticks of 2GB memory sticks).
Expansion Slots: Most modern motherboards will come with any different number of expansion slots. These generally include a number of PCI Express 2.0 x16 (, PCI Express x1, and PCI slots. You should pick your motherboard based on what peripherals you expect to be using with your Gaming PC, and what you may want to add in the future. This includes Graphics cards (most now use PCI Express 2.0 x16), soundcards, USB, Ethernet, Firewire and so on. Since we are interested in building Gaming PC’s here the suggestion is to always have room for a graphics card (or two).
Storage Devices: What storage devices does the motherboard support? Desktop motherboard will generally support a number of storage deice connectors like SATA (serial ATA) or PATA (Parallel ATA) to connect hard drives and optical drives. This will be important to know what types and how many of each the motherboard supports so you can then purchase a hard drive and optical drive compatible to the board. Usually you do not have to pay to close attention if you are purchasing say one hard drive and one optical drive, but if you wanted multiples you may want to check to see if you can. Most modern motherboard will have more SATA connectors as most hard drives and optical drives will require this now.
Onboard Audio: Nowadays motherboard will have pretty good onboard audio (which mean you do not have to purchase an external soundcard). If you are concerned about the quality of audio your motherboard you can do some research on the motherboard audio chipset to get a better understanding of what you will get.
Onboard Lan: Most motherboard will come with onboard Lan (Ethernet) installed on them so that you can easily connect to the internet, however not all motherboards will come with a wireless option so if this is a concern you may want to shop for wireless adapters to connect to you motherboard.
Rear Panel Ports: These will be the included ports with your motherboard such as USB, Audio, PS/2, Optical and so on. This can be completely up to you – Just make sure you have enough of what you want in order to connect what you need to your motherboard such as mice, keyboards, audio etc.
Internal I/O Connectors: These will be the in and out connectors that you can connect to your motherboard, such as external USB through your computer case etc.