In September 2012 my friend Bill and I assembled our own computers "from scratch". I learned a whole lot from the process, and would like to share. We often found it difficult to do solid research comparing and contrasting products and build components, so I figured I would consolidate our research into a publishable form that other people can use.
Things to remember: Bill and I weren't experts, and don't have a huge background in computers or electronics, we just wanted to try this for ourselves, so we did the research and so far the results have been SPECTACULAR. I highly recommend you do extra research on your own. Take what I say at face value; I might be wrong and the computer market is very dynamic. I found the following resources extremely helpful: https://www.youtube.com/watch?list=PL291F84A80CA32304&v... (newegg) http://www.pcgamer.com/2012/04/30/how-to-build-a-gaming... (PC Gamer)
The above are How-To's on building your own computer. Newegg.com was easily my favorite resource, although when it came to finding decent specs, both newegg and pcg (pc gamer) were disappointingly out of date. (It's possible they've been updated since.) As always, wikipedia is a fine knowledge base for practical stuff like this.
**Many manufacturers make the same components. For example, Samsung and Western Digital (WD) both make hard drives; MSI and EVGA both make NVIDIA graphics cards/drivers. This may/may not affect the component.**
Step One: Component List
I quickly realized I was completely lost inside a world I didn't understand, so I made a list of parts I needed, based largely off newegg's how-to video and disregarding parts I already owned:
Externals (CD/DVD Drive, etc)
It's EXTREMELY important to note that these are listed in the order I considered them, but you can't just buy parts individually and have them magically work together. They have to be compatible, and it takes a bit of digging sometimes to tell if they are or not.
Step Two: Size Constraints
It might sound a little backwards, but the first thing you have to consider is the end size of your rig. Mine had to fit under my desk, and I really didn't want to have to lug around a monster, so I opted for a mid-size build which is still somewhat hefty. Computer builds are defined by the size of your motherboard, which connects the entire computer together (we'll get to more of that later). Motherboard size affects whether or not you can plug in an extra graphics card, what kind of hard drives you can use, the configuration of plugs in the back, etc. There are 5-10 different sizes of motherboards. These sizes are referred to as "ATX". My computer case is a standard ATX tower (case, not an all-in-one like a Mac), but my motherboard is mini-ATX.
More info on ATX sizing here: https://en.wikipedia.org/wiki/ATX
TLDR: Know how big you want your computer to be. Check sizes on ALL your parts and make sure they fit inside the case.
Step Three: Motherboard and CPU
These two are inseparable. It would really suck to buy a really nice CPU and then have a motherboard not fit it. Motherboards tell you what chips they're designed for, just look for it. My rig has an MSI motherboard that's compatible with most intel chips. Intel i3, i5, and i7 chips have the LGA 1155 socket type. Don't be scared off just because the motherboard name sounds like a robot serial number. I don't know if there's an easier way to identify them.
My motherboard considerations:
CPU Socket Type (LGA 1155) -This is an intel chip socket. If you decide to use an AMD CPU, you're gonna have a bad time.
Sound compatibility (5.1) - This only matters if you have a nice sound system.
SATA Speed (6 Gb/s) - SATA cables talk to your hard drives & CD/DVD drives. Make sure those drives are compatible with that speed (SATA 6 is new ish).
Memory Slots RAM compatibility (DDR3 1866) - RAM is classified according to codes, most is DDR3 nowadays anyway, so make sure the RAM you get is compatible.
PCI slots (3.0 x2, normal x2) - PCI slots are like SATA slots but for video cards and other addons. PCI 3.0 is quite new, so make sure you can use it!
Form factor (mini ATX) - see above.
Your CPU does most of the work in the computer; it's basically the brain of the machine. CPU speed determines "how fast" your computer runs, and how fast it does certain operations. When people talk about number of "cores" in a CPU, they're talking about number of parallel operations executed at the same time. So the intel duo-core processor of several years ago had two cores, which let it do two operations at once, instead of one. Nowadays there are all sorts of multicore processors: mine is a quad-core. There are two major CPU makers out there: AMD and Intel. A little research shows that Intel dominates the desktop PC market, with AMD dragging behind in performance but for less money. This issue is hotly contested. Standard CPU speeds run anywhere from 2.0 to 3.0 GHz; though nowadays I think most are around the 3.0 GHz range (that's the number of executed operations: 3 with 9 zeroes after it). If you want a solid CPU for cheap, maybe a good AMD chip would do, but if you're looking for performance, then shell out for an Intel chip.
Why I think Intel is better: (skip this if you believe me)
Intel's chips feature "hyperthreading", which allows different cores to talk to each other much more effectively (something AMD seems not to have figured out yet), and use a lot less power for their output. For example, AMD's top chip that I could find has 8 cores and is advertised as running at 4.0 GHz, but newegg markets it at 3.1 -- AMD is showing the overclocked speed, which is like a turbo mode from F-Zero: the more you boost the more health you lose. More on that later. AMD also uses almost twice the power at 125W, which could really show later when you need a better power supply. so you might not actually be saving that much money.
When you start talking about CPU and video card speeds, everyone wants to know if something overclocks. "Overclocking" is like fine tuning an engine yourself. It's the process of making minute adjustments to the CPU settings like voltage to coax maximum performance from the chip. Manufacturers, realizing that people do this, often make it easier by designing modes that keep you from destroying the chip (which is not hard to do). This makes it less risky, but not necessarily safe: the chip is designed to run at a certain speed (not the overclock [OC] speed). The best analogy I can think of is F-Zero: the faster you boost, the faster you die. This isn't necessarily true, but it can be. Do your homework on this one before trying it. I recommend MSI Afterburner to get started: http://event.msi.com/vga/afterburner/overview.htm
So now you've hopefully chosen a CPU that gets some kind of decent speed (mine's a 3.5 GHz). The product page will tell you what kind of socket it needs (Intel's LGA 1155 is pretty common), so you can find a motherboard to match. Don't worry about getting a motherboard manufactured by the CPU maker -- just because Intel makes motherboards doesn't mean you need one of theirs. MSI made mine, and it works beautifully. If the CPU is the brain, the motherboard is the torso; everything connects to it and it keeps all the components working together harmoniously.
Cost so far:
Intel i7-3770k $330
MSI Z77MA-G45 $120
Step Four: RAM
RAM stands for Random Access Memory, and it helps your computer do simultaneous things. When you're running Photoshop, Chrome, Spotify, Word, a movie, and playing a game on the other screen, RAM helps keep all that running properly. Now your motherboard also determines how much RAM your computer can handle -- mine can only use 32GB, so it's foolish to try for something more. Nowadays RAM also comes in pairs and quads, so much like hyperthreading in CPU cores, buying a set of 2 or 4 RAM sticks will guarantee they work together efficiently. There's not much of a difference out there when it comes to manufacturer, so if there's one you like then go ahead and spring for them. Just make sure the RAM type you get is compatible in your motherboard (my RAM is type DDR3 1866). Make sure you have enough motherboard slots for the RAM you get.
Step Five: Graphics Card
This can be a big thing, especially if you're planning on using the rig for games. CPUs come with integrated video, which means you don't technically have to buy one, but it takes a huge toll on your CPU, and you can get awesome performance from external video cards. The two major competitors in this market are NVIDIA and AMD. This is again hotly contested, but I prefer NVIDIA for performance. To make this choice more difficult, game developers often pair with or test their games to work specifically on NVIDIA or AMD products, so the choice is really yours. EVGA, MSI, and Galaxy are 3rd party manufacturers that manufacture these chips with the necessary stuff on them. I think they're all priced about the same once you get to a certain performance level, but you can still get very solid cards for $100-$200. I bought a Galaxy NVIDIA GTX 550 Ti to go in my old computer, and it works great. It's not going to be running battlefield3 or far cry 3 on ultra graphics, but it does the job happily. For some more cash, you can go with what I got: an NVIDIA GTX 660 Ti. The Ti versions of NVIDIA's cards are normally known for being very stable, which is good because sometimes buying the very newest edition can end with a half-finished product. The GTX 660 Ti needs a PCI 3.0 slot to function - see motherboard section.
The next most important thing about graphics cards is drivers. Once you boot up your computer, you need to go to the website of your graphics card and download a driver to help it function (if it's not done automatically). For NVIDIA, stay away from the beta drivers. I've also had some problems with always having the newest driver, so sometimes it's safe to just update every other driver instead. Driver updates are often just tweaks to certain games anyway, so often they're not worth the trouble.
Step Six: Power Supply
The power supply is the heart of the beast. Make sure you count up the wattage draw from your other major compents and have some room to spare. We have a CPU drawing 77W. A google search (and help from Tom's Hardware) shows our video card is going to draw about 100-200W. (http://www.tomshardware.com/reviews/geforce-gtx-660-ti-...) So as long as we're safely above 300W we should be ok. True to form, we're going to blow that out of the park and look at Corsair's 850W behemoth. In general I wouldn't recommend anything below 400W to be safe, but I don't think you need anything near 1000W unless you intend to draw some serious freakin power. Things that matter are that little "80 gold certified" thing plastered all over the product I bought. That means it runs efficiently, which will save you money on your electricity bill over a non certified one. I chose a "modular" power supply because it's much much cleaner. If you pop your computer open and look at the power supply (it's a little cube and normally has a switch on the back, near the bottom of the tower -- that's where you plug in your tower's power cord), it's got this fugly mess of cables that are mostly but not all plugged in somewhere snaking all over the place like Medusa or the well of souls in Raiders of the Lost Ark. Modular power supplies let you choose which to plug in which saves you time, effort, and ultimately really helps airflow (more on that later). So I think it's solidly worth the money. This thing runs about $190.
Step Seven: Memory
There are a few options using the two types of memory out there. There are hard disk drives (HDDs), the good old stuff we've been using for memory since I was born, and there's this new-fangled thing called a solid state drive (SSD). Solid state drives are basically flash memory (like thumb drives) in large form. SSDs are stupendously fast, but they're also stupendously expensive compared to HDDs. SSDs are fast primarily because they dont have to spin up -- HDDs have a physical arm that has to move around a disk to read/write stuff, that's the sound you get when your computer wakes up -- but they also store memory differently, which allows them to access it more quickly. There are a number of ways to supposedly get the speed of a SSD with the size of a HDD using methods like RAID, but I don't really know anything about that (sorry). SSD space is about $1/GB right now, plus or minus ten cents. Any deals haven't been very good, but will it will get better over time. My rig has a SSD running the operating system (hello, welcome to windows, internet, etc) and I keep everything else on a large HDD. If you have the money to shell out on a big SSD, go for it because my computer can go from off to in-game in about 90 seconds. That's a conservative estimate.
Samsung makes good SSDs and HDDs, although they're not without their problems. OCZ makes good SSDs as well, and WD has good HDDs. Newegg has solid reviews on all products (if anything has fewer than 25 reviews you should probably look at something else). For comparison, my Samsung 128GB SSD costs $110, the same as a Seagate 2TB HDD.
Cost so far:
Intel i7-3770k $330
MSI Z77MA-G45 $120
G.Skill DDR3 1866 4x4GB $100
NVIDIA GTX 660 TI $310
Corsair HX850 $190
Samsung 830 128GB SSD $110
Throw a few pence towards a little CD/DVD burner; speeds don't matter really unless you're a DJ. I'm using mine to watch movies. Don't waste money on a Blu-Ray player unless you really need it. I got a pretty generic ASUS model: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Step Eight: Airflow & Case
Airflow can really affect your computer performance, especially if you stick it in the back of a desk alcove or in a tight space. High end electronics are going to generate heat and it needs to be moved. There are many configurations, which depend mainly on your case and what fan comes with your CPU. Bill and I decided to get an extra fan for the CPU because frankly the one that comes with it is like bringing a Prius to a muscle car show. For relatively cheap, you can get a nice fan that will do a heckuva lot more for your CPU than that little bit of plastic that ships with it. Copper and gold are awesome conductors, and I recommend Zalman's product: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Now you've got pretty much everything else worked out, it's time to look at cases. Recall the earlier discussion about ATX sizing -- if you have a mid-ATX motherboard you CANNOT use a mini-ATX case. I chose a Corsair Carbide series. It is compatible with mid and mini-ATX motherboards. It also lets you run all the cords behind the motherboard. As discussed earlier, this keeps the computer cleaner and lets air in more easily. It also comes with one big fan on the side, two in the front and one in the back which practically throws air through the PC. I like the cleanable vents that pop in and out. The case is metal, not plastic, which makes it heavy but also sturdy. It's also nearly infinitely customizable, letting you put the power supply at the top or bottom and choose how your air flows, with space for 4 more fans if you choose or even a liquid cooling system (more trouble than it's worth - trust me on this one). Also it looks boss.