How to Build a Computer from Scratch

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Although desktop use is declining in favor of mobile devices, desktops still hold two key advantages: they can be far more powerful, and they are highly customizable. Mobile devices generally aren’t built to be altered. Some laptops have slots to put in additional memory or small modules, but beyond that there’s not much you can upgrade easily. For smartphones, if you need better hardware, your only choice is to buy a newer model. With PCs, upgrading your hardware is often as simple as opening the case, swapping in some new parts, and installing their drivers. You can even build an entire computer from scratch, all customized to your specific requirements. Here’s a guide on how to do just that.

What Is Your Computer For?

The first thing to decide when you build your computer from scratch is what you’re going to use it for. You could just go for the best of everything, but not only will it be extraordinarily expensive, it would be a huge waste of money if you don’t even use its full capabilities. That’s why you should focus only on the parts that are important for your PC’s purpose instead. Here are some common types of home computers and what you should focus on when building them:

“Graphics” computer: This is a computer for graphics designers, CAD (computer-aided design) engineers, architects, and other professionals who work with graphics-heavy programs. For this kind of computer, focus on a good multi-core CPU, a high-end graphics card, and lots of RAM.
Audio/video computer: This computer is for musicians, videographers, and others who work in the audio/video industry. For this one, focus on a good graphics card, a good sound card, large and fast hard drives, and the ability to support multiple monitors. Since this is a field that deals with audio recordings, you’ll also want to make sure that your CPU’s cooling system is quiet.
Gaming computer: Today’s games require a monstrous amount of computing power to run at a high frame rate (FPS) with the graphics settings at max. Focus on a good multi-core CPU, a high-end graphics card, a good amount of RAM, a good cooling system (consider liquid cooling systems if you’re running a really high-power setup), and a decent power supply unit. You could also look for a good sound card, but personally, I don’t find this to be necessary (just have a good set of speakers or headphones). Power requirements, heat, and noise are all things you should consider carefully with this kind of computer. Also note that gaming technology advances quickly, so you don’t want to build something that just meets the minimum requirements of today’s games.
Home theater computer: This kind of computer is for media enthusiasts who want to stream or watch HD content at home or elsewhere. For this computer, focus on surround sound audio capability, compatibility with the kinds of inputs and outputs you want, a TV tuner if you need it, and a quiet CPU cooling system.

Selecting the Parts for Your Computer

When selecting the actual parts of your PC, the most important thing to check for is compatibility. There are a huge variety of parts out there, so you’ll want to use a part manager like PCPartPicker.com (website here) to check if all the stuff you want will work together. Compatibility also applies to your operating system. A friend of mine who built a new computer a few years ago found out about this the hard way when the motherboard he chose only had USB 3.0 ports, and he installed Windows 7 on it. Windows 7 doesn’t have USB 3.0 support out of the box, so he couldn’t use his keyboard or mouse until he did a few workarounds to update his computer. Ouch. Make absolutely sure that you plan out your new PC carefully. Here’s a general guide on how to pick the parts for your computer:

CPU

The two main CPU companies are Intel and AMD. Both of them have a huge number of models, so I’ll just go over the main chips you’re likely to use: Intel’s Core line and AMD’s Ryzen line.

For Intel, their Core line is split into the Intel Core i3 (good performance), i5 (high performance), i7 (very high performance), and i9 (best performance) brands. The 4-digit number that follows is formatted like this: first number is the generation of the chip, the next 3 are the model number (higher model numbers are generally better with more cores and/or higher clock speeds). Sometimes there’s also a letter following the number (usually “K”, meaning the processor is unlocked and thus able to be overclocked or underclocked).

AMD’s Ryzen line is similarly split into the Ryzen 3 (good performance), 5 (high performance), 7 (very high performance) brands. The 4-digit number that follows is formatted in the same way as Intel’s Core line. Sometimes you might see a letter at the end (usually “X”, which means faster clock speed). Unlike Intel, most AMD chips are unlocked.

The generation of the chip can mean a big jump in performance because they represent changes in the chip’s architecture. For example, a high-generation i5 chip can outperform a lower generation i7 chip. Always look at the specs to know exactly what you’re getting.

The important specs to pay attention to are clock speed, number of cores, and number of threads. Clock speed is the how fast the chip operates in Hz (higher is better; base speed is minimum and turbo is maximum). The core count is the number of individual processors on the chip (most have between 4 to 8 with 32 being the max at the moment). Closely related to this is the thread count, which is the number of independent processes the CPU can handle simultaneously. It’s equal to the number of cores, but if the CPU has Hyper-Threading (Intel) or Simultaneous Multithreading aka SMT (AMD), each core can process two threads. More threads is generally better, but you’ll only really see a big improvement if you’re running heavily threaded programs that can take advantage of it, like video editors.

At the moment, Intel’s CPUs hold the edge in processor speed (better for general use and gaming), but AMD’s CPUs have more cores (better for multitasking/heavily-threaded programs).

A Note on Overclocking

As you’ve read, a few of Intel’s CPUs and most of AMD’s are unlocked to allow overclocking. Overclocking a CPU means running it at a higher clock speed than it was originally intended for. However, it’s not something that should be attempted lightly. Overclocking increases the amount of electricity used and the amount of heat produced by the chip, and if you don’t know exactly what you’re doing, your new PC could literally go up in smoke. It’s also pretty hard on the CPU and will wear it out. That’s why both Intel and AMD will void the warranty on the chip if you bust it when it’s overclocked. Overclocked systems are also much more prone to data corruption and crashes. For the general user, I highly discourage it.

CPU Cooling System

CPUs get pretty hot during use. To get rid of this waste heat, you need to install some kind of cooling system on top of it. The most basic version of this is a “block” of metal fins (usually aluminum and/or copper) called a heat sink connected to a fan. For most cases, this is enough. But if you’re running high-performance systems, you’ll probably want to get one that has a powerful fan or has multiple fans. Another thing to note is that it seems blowing air onto the heat sink is better at removing heat when the heat sink’s fin density is low, and blowing air away from the heat sink is better when the fin density is high.

For the highest performance systems like those used for gaming, you might want to consider a liquid cooling system. These systems pump water through tubes across various computer components and then cool it off elsewhere. Although they’re more efficient and quieter than fans, they’re also much more expensive and harder to maintain.

To determine what cooling system to get, look at your CPU’s thermal design power (TDP). This is the maximum amount of heat the CPU generates at its normal clock speed in watts (W). Your cooling system has to be able to handle this number or more.

Graphics Card

For a general use computer, you can probably get by without a dedicated graphics card. But for gaming and other graphic-intensive programs, you really need a good one. The two main companies here are Nvidia and AMD. Like CPUs, there are a lot of models out there, so I’ll just be covering the ones that you’re most likely to use: Nvidia’s GeForce line and AMD’s Radeon line.

Nvidia names their GeForce cards like this: a brand name (GT for low-end, GTX for mid to high-end, and RTX for their new 20 series) followed by a 3 to 4-digit number. The first digit (or first two for 10 and above) indicates the architecture of the card: 9 is Maxwell, 10 is Pascal, and 20 is Turing. The other two digits are the model number with higher numbers being better. There might be an “M” at the end of the number, but you can ignore these because it means the card is meant for mobile devices. A “Ti” at the end of the number means it’s a faster version.

AMD follows a similar pattern for their Radeon cards: a brand name (R5 for low-end, R7 for mid-range, R9 for high-end, and RX for highest-tier) followed by a 3 digit number. The first digit is the generation of the card, and the next two are the model number with higher numbers being better. An “M” in the front of the number indicates that it’s a mobile version, and an “X” at the end of the number means that it’s a faster version. AMD’s next newest card, the Vega line, breaks this naming pattern. It consists of the brand name, RX, followed by “Vega” and a number that indicates how many compute units (CU) it has. CU is a term AMD uses in their Graphics Core Next (GCN) architecture (one CU consists of 64 shader processors and 4 texture mapping units). The “Liquid” version means that it’s liquid-cooled (faster). AMD’s very latest card breaks the pattern again and is just called Radeon VII.

Throughout the years, Nvidia’s graphics cards were known to be more powerful, while AMD’s were known to be less expensive. For now, the two have pretty comparable products at the same price point. Which company’s product to go for really depends on your budget and purpose. If you want the absolute best, go for Nvidia. If you just want good performance for a reasonable price, AMD’s cards are better in that range.

The specs you should pay attention to for graphics cards are TDP, memory, interface, outputs, and multiple graphics card support.

TDP: This is the thermal design power. Like the CPU spec, it measures the maximum heat generated during normal use in watts. Graphics cards typically come with their own cooling systems, so it’s not something you need to account for. But if it’s high, and you plan to be using your PC for high-performance tasks, you might want to consider additional cooling measures like an additional fan to blow air out of the case.
Memory: Graphics cards have their own memory to aid in processing graphics. The latest standard is GDDR6. More memory is better but generally, the memory on the card is already sized for the card’s tasks. For example, if a graphics card is fast enough for a particular program, the amount of memory on it will be enough, too.
Interface: This is a motherboard consideration issue. Graphics cards go into PCIe slots (most are PCIe x16), but some cards are large and may interfere with other devices in your other PCIe slots. Make sure your motherboard has enough room to fit your card and all the other things you want to put in it.
Outputs: If you want to have multiple monitors, you need to pay attention to what kinds of outputs the card has. An adapter can help with a mismatch between your card’s ports and your monitors’, but you need to have at least as many outputs as monitors and make sure that the card can support that many.
Multiple graphics card support: This is the ability to work with another graphics card to boost performance. Nvidia’s term for this is Scalable Link Interface (SLI) and AMD’s term is Crossfire. Having multiple graphics cards with this feature can really boost the performance of games and other demanding programs.

Memory (RAM)

This is essentially the “working memory” of your computer. It’s used to store data that the computer is using at the moment. As a general rule of thumb, you need 8GB for basic use, 12-16 GB for heavier use (high-end gaming, video and photo editing, graphics design), 32 GB for multitasking with demanding programs and large files, and 64 GB for high-end design like CAD and computer animation or for very demanding programs like analysis software.

The latest standard for RAM is DDR4. The specs you should pay attention to are the clock speed and the CAS latency. A higher clock speed is better, while a lower latency (the number of clock cycles between telling it to get data and it producing it) is better. RAM modules are typically sold in kits of 2 or more because motherboards usually link the slots in channels. The most common is dual-channel, but triple and quad-channel also exist. Always use the exact same RAM module in linked slots to ensure optimal performance.

Storage

Now to pick the hard drive. There are two main choices for hard drives: mechanical and solid state. Mechanical hard drives have been around for decades. They’re the ones with the spinning disks (platters). Mechanical hard drives are cheap and have huge capacities. But the main drawback is that they’re relatively slow. Solid state drives are new and very fast. But the drawback is that they are way more expensive than mechanical hard drives of the same size. Which one you choose is going to depend on your purpose and budget. If you’re just using it for regular activities or for things that don’t require high speed, a mechanical hard drive is a reliable option. For demanding programs, you should consider a solid state drive.

Keep in mind that you aren’t limited to just one hard drive. You could get two hard drives, one solid state and one mechanical and get the best of both. Just put the heavy use programs and operating system on the solid state drive and all the pictures, movies, documents, and other low maintenance stuff on the mechanical one. If you don’t like doing this manually, it’s possible to link them together into one hybrid volume using your operating system. There are also hybrid drives available that combine some of the speed of a solid state drive with the storage capacity of a mechanical drive (a mechanical hard drive combined with a small solid state cache).

If you don’t have the money for a large solid state drive but want the speed of one, Intel has recently introduced a new technology called Optane. Optane allows a regular mechanical hard drive to approach solid state speeds. It’s available as a module that goes into the M.2 slot on your motherboard and is only compatible with 7^th gen and higher Intel CPUs (along with a compatible motherboard) and Windows 10.

Optical Drive

This part is just your CD or DVD drive. Obviously, you’ll need one if you want to read CDs and DVDs. With cloud computing taking over, running software from CDs and DVDs is becoming less common. Depending on your PC’s use, you may not even need one. But in the cases where, for example, your operating system backup disk is on a DVD or you want to be able to watch DVD movies or play/burn music CDs, you’ll need one.

Motherboard

Now that you have all your vital parts picked out, picking a motherboard to put all of it on is just an issue of compatibility. If you’re using a part manager, it will tell you whether your motherboard is compatible with everything or not. If you’re not, make sure that the motherboard has the right CPU socket and chipset, the proper connections for your hard drives and optical drives, the correct number of slots for your graphics cards/RAM modules/other devices, the correct ports for your speakers/keyboard/mouse/other peripherals, and is big enough so that everything fits.

Power Supply (PSU)

Your new PC won’t run without power, so the last internal component to pick is the power supply. To figure out what power supply to get, first you total up the power requirements for all your components (a part manager will do this for you). This will give you a rough estimate of the total power required from the power supply. Next, as a general rule of thumb, take that number and multiply it by 1.6. This new number is the one you should base your power supply on. The power supply must produce this amount or more. The reason you want to overcompensate on power is because your system will crash if its components aren’t getting enough.

Case

Now for the last part: the case. This part just needs to be compatible with your motherboard (the motherboard needs to be attached to the case) and be large enough to hold your hard drives/optical drives and cooling system. You can also chose one that has various LEDs or other displays on it. Just make sure your motherboard has the proper connections. Once you’ve finished checking for compatibility, you can pick a case to make your new PC look as awesome as you want.

Additional Tips

Plan a “full” system when you build your computer from scratch. What I mean by this is you should make sure all components are of similar performance levels. For example, you shouldn’t pair a powerful CPU with low RAM or a weak GPU. You’ll be hindering your powerful components and wasting money.
If you can afford it, pick components that are powerful by today’s standards. Since technology advances pretty quickly, what’s powerful today will be average a two or three years later and will be weak (if not unusable) a few more years later. You want to “future-proof” your system, that is to make it stay technologically relevant for as long as possible so that you don’t have to shell out for another new system soon.
When attaching a heat sink to the CPU, don’t forget to put thermal paste on the CPU. Thermal paste is absolutely vital to ensuring that the heat from the CPU is transferred to the heat sink properly. You want an even layer of paste that covers the entire area where the heat sink and CPU touch (no air pockets!).
Make sure all components are properly connected before turning on your computer. I once fried a motherboard when I was a kid because I didn’t quite push a RAM card all the way into its slot. Don’t let it happen to you.
Wear an anti-static band when handling components. Static electricity can damage the sensitive electronics in many PC parts.
Don’t handle any component by its metal contacts. You could transmit static electricity to the device and damage it. Also, the oil on your skin could change the conductivity of the contacts, which would result in abnormal performance.
Make sure that your power supply is set to the proper input voltage before you turn the computer on. If it’s not correct, you could totally fry your system. The 115V setting is for the US and the 230V setting is for most of the rest of the world.

Yue’s Recommendation

Although you can find PC parts at many stores, I suggest getting your parts from as few retailers as possible. The reason for this is shipping costs. Not all retailers have free shipping, so even if you find a part for a lower price somewhere else, if you have to pay more for shipping, you could nullify those savings. This is one reason why I recommend Amazon as the place to find all your parts. Not only do they have a huge selection, they also have decent prices. And if you buy directly from Amazon, your order is practically guaranteed to qualify for free shipping. The other reason is the return process. Amazon offers various return options, such as Amazon Locker/Campus, in addition to the standard return-by-mail process. This makes returning parts that don’t work or don’t fit a breeze compared to other online retailers.