After you choose your processor, you can move onto the motherboard. Go back and look at the specs of your chosen processor. You will need the name/number of the type of port that it uses. This is the port that must be on your chosen motherboard so that it will fit. ex. The newer model AMD processors use a port called AM3(+). The plus just adds additional functionality, especially for gamers, but you can match up a + model port with a non + model CPU and vice versa without a problem as long as the numbers/letters before the + are the same. When researching motherboards, you will need to know what brands are the most reliable and best suited for what you wish to use it for. Some of the top brands include ASUS, Gigabyte, MSI, ASRock, and EVGA. For gamers, I would suggest you go with ASUS, MSI, Gigabyte, or EVGA. Be sure to check out the reviews and compare before purchasing.
Now, looking back at the paragraph on ram cards, we will use the specs on the ram to help shape our motherboard search. Which DDR ram did you choose? What was its clock speed? When looking at motherboards, it will tell you what type of ram it supports and how fast it can run the cards. Now before you think the motherboard can increase your ram cards clocked speed (over-clock), that is not generally true. If your ram cards say that they run at 2400MHz, and your motherboard says 2800MHz, it just means that it can support any card up to the speed. Your ram cards will still work of course. Now lets say that your ram cards run at 1800MHz and your motherboard can only support up to 1600MHz, your ram cards will still work here as well .The motherboard will just run the ram cards slower than what they are capable of. It won't hurt the cards at all. Be sure to double check the type of ram you use so you are sure that it will fit in your motherboard.
Next, you must look at what type of PCI port your graphics card uses (Explained in part 4). Some graphics cards will use PCI-Express x 16 while others may use the standard PCI. Choose how many PCI and what type you will need for your PC.
Next is deciding the type of ports you wish to have on the rear of your motherboard. These ports will sit flush with the rear of your PC case so you can plug in all of your components. Ex. mouse, keyboard, monitor, etc. So choose how many USB ports and such that you wish to have on it. Every motherboard will have USB port(s), an Ethernet port (For wired internet), an auxiliary port (For audio), and other ports for added uses. Some motherboards will also come with an integrated graphics card, so they will have a port to connect your monitor too, either VGA or DVI. Only some motherboards have integrated graphics and I only recommend using it for extremely lenient work. Multiple monitors, heavy multi-tasking, and gaming will not work, if at the very least not well, with the integrated graphics.