This Instructable is for gamers who have finally reached the conclusion that store bought computers are not capable of meeting gamers needs and are looking to build their first gaming computer.
A lot of this is pretty basic,but when you don't know what the ports are or what you're looking for it can get very confusing very fast.
Step 1: Choosing Parts
The first step of building a computer is making sure what you're building will give you the performance you need. The point of building a computer is higher performance, so make sure you're getting the right parts for the performance you need.
A quick rundown of the important parts:
Motherboard: The motherboard is the backbone of your computer. The only thing you're really looking for is enough of the correct ports. As long as everything's compatible with your motherboard, it's good. The easy way to ensure that everything works with your motherboard is to use an online parts website like pcpartpicker.com. Press the compatibility button and everything that you can select will work with the motherboard you've selected, but make sure you have enough USB ports on the outside
GPU (graphics card): Your graphics card is exactly what you would expect: power for your graphics. The resolution you are capable of outputting to your monitor and the lag induced by graphical rendering are the two things governed by your graphics card. Although this is optional in some cases due to on-board graphics, if you're building a computer for high specs, you will need a separate graphics card. Graphics related lag is probably the most common lag, and if you aren't using a gaming computer, it's what will make games unplayable. Graphics cards are more defined by their series than by their specs. The two big producers of graphics cards are Intel and AMD, and they each have sets of chips that indicate their power. For Intel, the series get better as you go up the hundreds digit; the chips in the 200 level are much worse than the 700 level. For AMD, the series are R#, and the higher number is the better series. There are of course better and worse cards within a series, and you can look at the reviews of each to find which are better.
CPU (processor): Your CPU is what deals with the ones and zeros on a computer; it governs the speed of the programs you're running. The reason that a bad graphics card induces lag is because when your GPU falls behind, your CPU has to pick up the slack. The two big numbers you're looking for on CPU is the number of cores and clock speed. The number of cores is simply how many things it can do at a time. Think of each core as a separate processor, and you can have 4 or 8 running simultaneously on your computer working together to get things done. More cores = more power. Clock speed is basically the speed at which the CPU runs. The higher your clock speed, the faster each of the cores run.
RAM (memory): RAM is basically temporary data; how many variables are being stored temporarily for the programs you're using. To be completely honest, there are multiple variables that matter about RAM, but the only thing you need to look at the size. 4GB vs 8GB vs 16GB is the only thing you truly need to ask yourself. If you're going for a high cost build you can go for DDR4 RAM as opposed to the standard DDR3 which makes it faster, but mostly it's just the size. To figure out how much RAM you would need, just open your task manager and add up all the RAM usage totals which is usually the second column. It is difficult to use more than 8GB of ram, unless you're doing something like 3D rendering or video encoding, so 8 is usually enough.
HDD (Hard drive): How much space do you need? your hard drive governs how many things you can save to your computer. more games, more videos, more applications, and more pictures all need more space so pick your size according to that. If you save a lot of things to your computer you might want more space, or if you mostly watch your videos on YouTube then you won't need as much space. The standard right now is 1TB hard drives and storage space is the only number that really matters (as long as you pay attention to not buy a laptop hard drive!). for most people its enough space, but its really up to you. If you want to look at the speed of the hard drive to pick one that goes faster you can, but if you're looking for that you might consider substituting your hard drive for an SSD (see below)
SSD (solid state drive) (optional): An SSD is just a hard drive that uses semisolids to store data instead of a spinning disk. it is a part that can be used either instead or alongside of a hard drive, and plugs in the same exact way. It functions the same way an HDD does, but it runs faster and has less space. What faster storage means is that your programs and possibly your operating system will boot faster. This can drastically decrease starting times for games and turning on your computer. If those 15 seconds of downtime bother you, get an SSD, if not, save the money and just get a hard drive. What many gamers do is they put their high end games with big start times as well as their operating system on their SSD, and then use their hard drive to store pictures, low end games, and other programs. Keep in mind that this method requires two SATA ports on your motherboard.
PSU (power supply): your PSU is what distributes electricity to each part of your computer. PSUs are differentiated by grade and power. Grade (none/bronze/silver/gold/platinum) determines the efficiency of your power. Every conversion of power from one form to another causes energy loss, and PSUs are no different. the higher your grade is, the less energy is lost, and therefore lowering your energy bill. The power of your PSU is anythign above the required power of your machine. Many sites such as the aforementioned pcpartpicker.com have built in power calculators that you can use to determine how much power you need for all of your parts, or you could just find one easily on google. Anything above that number is fine. The last, and arguably most important element of a PSU is modularity. A modular power source lets you remove the cables you aren't using (which is usually about half for a 6-900 dollar build), which is huge. Box clutter is a serious problem, and can lead to overheating, as well as making it infuriating to find anything in the case.
Case: Always make sure everything you have will fit inside your case. Some smaller or older cases don't have room for a high end graphics card, and some are too compact for some motherboards. Other than that, just pick what looks the coolest.
Heatsink: Although technically not a part in and of itself, it is very important. Many CPUs will have their own heatsink, and so will everty high end graphics card. If you believe you will have heat problems (read: pushing the system to its limits) then you should probably get a secondary fan or liquid cooling inside your case.
There are many resources out there to help you choose what parts you want. The logicalInstruments price guide is a good place to show you what price ranges you're looking for (http://www.logicalincrements.com/), and if you want some good feedback on some tentative ideas reddit.com/r/buildapc is a great resource to look at. They have a very knowledgeable user base, and great beginners guides.
Step 2: Installing CPU
before you put anything in your box you want to have your CPU attached to your motherboard. The first and most important rule from here on out is you always have metal objects with you, and you constantly touch them. Having a static charge while touching your CPU can completely fry it during installation. This can happen with other parts, but the CPU is by far the most sensitive. Do your work on a metal table, on a metal chair, constantly touch your screwdriver, or whatever you need to do to constantly ground yourself and keep your static charge as low as possible. A great way to keep yourself grounded is to have an anti static wristband. Never wear socks, work on a carpeted floor, and most importantly keep the area clear. Someone bumping your arm will almost definitely incur hundreds of dollars of damage.
The CPU slot is is square bracket with the latch similar to the one in the picture. The latch differs by motherboard, but you can figure out how to open most by looking at it (some have a wire like goes along the bottom of the picture, some you push in and they open like a old Nintendo game or the memory card for your phone). You may have a plastic cover over it, just throw that away. Before you open and touch the CPU keep in mind you never touch anything that is not green. green is the silicon base and the only thing that isn't electronic. You should notice in the corner of the CPU that there is an arrow, and on your motherboard there will be a similar arrow. Align these two when you put the CPU into the opened latch, then close the latch on the CPU. After installing the CPU, you should see 4 small holes around the area that you just installed the CPU in. These are the holes that you use to install the heat sink over your CPU. Near the CPU (usually towards the outside of the board) you should see four pin ports that the heat sink plugs into. Whichever side the ports are on is the side the wires for the heat sink should be oriented towards. After you orient the heat sink just screw it in and plug it in
Step 3: Installing Motherboard
for the entirety of this Instructable, your case will be opened and on its side. The "bottom" of your computer is now officially the side panel that your motherboard mounts on (usually the right panel).
On the new bottom of your computer you will see pegs that stick out. These pegs are what the motherboard rests on, because the electronics on the bottom of the board prevent it from lying flat. Line the pegs up with the holes in your motherboard. To get the orientation right, there should be one side of the motherboard with all of your USB ports, audio ports, etc. That side is oriented to the back of your computer and sticks out into the back panel. Take note of which holes in the motherboard have pegs under them (not all will), and screw down those locations.
Step 4: Installing RAM
RAM is generally easy to spot. Ram is the long rectangular piece, and the two (or four) long rectangular pieces on your motherboard are rather apparent due to their size.
Step 5: Installing PSU
the slot for PSU to go differs by case. Some have it in a bracket attached to the top/bottom, some have it just bolted to the top or side, but they all have to line up with the slot on the back of the box. After you screw it in place, you'll have to find the motherboard power. This should easily be the biggest cord coming out of your PSU and it should look like above. The port on the motherboard is large, and quite obvious. You will also need to put the power for the outputs on the back of your computer (USBs, audio, ethernet, etc)
Step 6: Install GPU
Your graphics card is also something that will be aligned out the back of the box. If you have barriers on the back of the box, they will have to be removed. Some graphics cards will just screw into the back of the box, some won't it all depends on the chipset you get. Put it in the long rectangular slot, and make sure that all the pressure is perpendicular to the motherboard. The connection can break if you don't push straight down. Most graphics cards will also have to be plugged into your PSU.
Step 7: Install Hard Drive
the hard drive should be 3.5" or computer sized. Assuming you didn't buy a laptop sized hard drive, you should see a cubic slot where you can just put the hard drive in and screw it in place. Then you need to plug in both the PSU and motherboard. The larger plug is for PSU, and the smaller one goes to your motherboard.
If you opted to get an SSD alongside or instead of a hard drive the ports are the same, but it won't screw into your standard bracket. You'll either need to buy a mounting bracket (something like http://www.amazon.com/SABRENT-Inches-Internal-Mounting-BK-HDDH/dp/B00G57BN1M/ref=sr_1_1?ie=UTF8&qid=1438477097&sr=8-1&keywords=ssd+mount+bracket) or there are some nicer brackets you can plug your SSD into that will hold it in place.
Step 8: Close Up Your Box
If you want some optical drives, line them up with the slots the case provides you, then plug into your PSU. If you want another fan, you can mount it to the back grills and plug it into the port that looks like the one used for your CPU fan, but beyond that just close up the box, throw in the windows install disc and start up your new computer