How to Build a Custom Computer!

Introduction: How to Build a Custom Computer!

This Instructable will show how to assemble a custom computer from it's basic parts available online or in electronic retail stores.  Manual assembly has a number of benefits including lower cost, the power to build a machine tailed to the user's needs, and the pride of having completed a technical project!  Total assembly time should take no longer than 2 hours for a beginner working solo.

Before starting this build, you must choose your parts.  It is important to make sure all parts are compatible with each other.  To meet this requirement, there exist  a number of helpful tools for beginners:

1: is a great website for comparing different builds.  This will ensure your parts are compatible, of good quality, and most importantly within your budget!

2: Barebone Kits:  Major online component vendors and both offer a wide variety of barebone kits.  These kits are chosen by professionals, and provide an easy way to quickly bulk order one computer worth of parts.  The kits generally provide what you'll need for this build and span all price ranges.

Refer to step one to ensure you have all parts and tools required and enjoy the build!

Step 1: Identify Parts and Tools!

Here is what you will need to complete this build:

1 Case with Power Supply  -- Most cases come with power supply pre-installed
1 Heatsink
1 Motherboard
1 Hard Disk Drive (HDD) with SATA Cables
1 or more sticks of RAM
1 Video Card
1 Optical Drive (DVD)
1 Phillips head screwdriver
All of these parts are available for a wide variety of prices on websites like and  

Step 2: Installing the Motherboard

CAUTION:Before you do anything, it is vitally important to properly ground yourself.  The slightest static shock can have a devastating effect on these parts and they must be handled with care.  I generally ground myself by touching the screw on a standard outlet.  This should be done repeatedly throughout the build to be sure you are not shocking the components.

Once you are grounded, have a look inside the case.  You will see a number of holes, some labeled ATX or microATX, that corresponds to the size of your motherboard.  If you pick up the motherboard and slowly lower it in the case, it is easy to see which holes correspond the size of your motherboard.  Before placing the motherboard however, there are intermediate screws that need to be placed to keep the motherboard raised off of the metal case.  This type of screw is shown in an image above. once you have the proper intermediate screws installed, you can place the motherboard on top of them and screw it down with your standard dome top screws.  

Note: Sometimes you are left with an extra screw, or perhaps an extra hole.  Such is life.  As long as the motherboard is secured in the case and doesn't wiggle, you are okay to continue to the next step.

Step 3: Inserting the CPU

Installing the CPU is a quick and simple task, but must be done with extreme caution.  First, locate the small square on the motherboard where the CPU should be inserted.  You will see a small white triangle in the bottom left corner, it is important that this is matched with the small triangle on the corner of your CPU.  Simply place the CPU onto the slot and GENTLY press down.  If the CPU is not lined up correctly, do not attempt to slide it into place.  Pick it up and retry.  A single bent pin will render the CPU worthless, so be sure you are correct before pressing.  You will feel the CPU pins slide into their slots and then stop.  The mechanism for securing the CPU may be different on different motherboards, but I have outlined how it is secured on this motherboard in an image above.  It is as simple as lowering the metal bracket and sliding it under the circular bolt, then applying firm pressure to the pin adjacent until it is secured under the bracket.

Step 4: Installing the Heatsink

The heatsink securing mechanism will almost certainly be different for different CPU-heatsink combinations, so always consult the manual if things do not look similar.  Here are the steps for my heatsink.

First, apply thermal paste to the top of the CPU.  This is an important step and is as simple as spreading the provided paste evenly between the CPU and heatsink.  Next place the heatsink on top of the entire CPU mechanism, aligning the four corner pins with the holes in the motherboard.   At the start, the pins should be turned opposite the arrows and have full range of vertical motion.  Once the pins are aligned with the holes, apply firm pressure until you feel the pin "click" through the motherboard hole.  Do this for each pin, and then twist each pin in the direction of the arrow to fully secure the heatsink.  Next, locate the 4 pin power adapter (labeled CPU fan) on the motherboard and insert the power cable (shown in pictures 2 and 3).  

Step 5: Install the RAM

Installing RAM is a fairly trivial step. Locate the ports, generally near the CPU, that are approximately the same size and shape as your RAM stick.  Pull back the white locking mechanisms into the open position.  Next, note which direction the RAM should be oriented by aligning the notch in the port with the notch in the RAM (at about 3/4 of the length).  Place the RAM stick in the port and apply firm pressure to the top left of the stick until the white pin locks itself into place, then apply firm pressure to the other side.  After this, it should be securely locked into place.  Repeat for each stick.

Step 6: Installing the Hard Drive

Installing the hard drive is another very simple step.  Simply slide the hard drive into the slots of identical width.  These HDD bays may be located on the top or bottom of your case, almost always on the front.  Simply line up the holes in the case with the screw holes in the HDD and insert your screws.  The pictures show two hard drives being installed, most builds only require one.

Step 7: Installing the Optical Drive (DVD)

Installing the optical drive is almost identical to the last step.  Simply slide the drive into the case, and insert the screws.  

NOTE: It is often easier to slide this drive through the front of the case based on the location of your power supply.  

Step 8: Installing the Video Card

Installing the video card is most similar to installing the RAM.  Locate the slot on the motherboard that matches the bottom of your video card.  Align the notch in the slot with the notch on the bottom of the card, place it on top, and apply firm pressure until it clicks into place.  

Step 9: Case Fans

Most modern cases will have multiple spots to install (additional) fans.  When purchasing, note the size of the fan and consult the case manual to ensure you have spots that match this size.  Then simply screw the fan into the case and plug it in to one of the cords coming out of the power supply. 

General theory is to have fans at the front blowing cool air in and fans located at the back blowing hot air out.  

Step 10: Power

Powering the components in your computer is a simple case of mix and match.  There will be a fairly large array of cords coming out of the power supply.  In general, if it fits, it's fine.  

The first and largest cord will be the 20/24 pin to power the motherboard (picture one).  This connection usually takes a fair amount of pressure to insert.  There is also a 12V motherboard power connector shown in picture 4.  This 4 pin connector could be located anywhere on the motherboard, in this case it is near the heatsink.  

The hard drive(s) will have two connections, one SATA cable (red in this case, picture 2) for information. This connection runs from the back of the hard drive to the motherboard, simply match the notches. The HDD will also have one power cable coming from the power supply.   The optical drive will be connected to the power supply in an identical manner.

If you have a fairly powerful video card, this may require an additional four pin connector from the power supply.  This will be located on the back/top of the card (picture 5).

Step 11: Other Connections

You may have noticed unidentified cords zooming in and out of the previous pictures.  These cords are the case to motherboard connections and control things like LED's, the power/reset button, USB ports etc.   These connections vary so widely from case to case and motherboard to motherboard that the only way to make them is to consult your manuals.  I have included a picture of a typical motherboard - case connection chart to show you what to look for.

Once you have located these instructions in the manual, it's a matter of reading the wires coming out of the case and placing them on the correct motherboard pins.  This step can be frustrating as the pins are very small, but is necessary to implement all the features of your case.


Congratulations! Your custom built computer is now ready to rock and roll.  Install the operating system and enjoy the fruits of your labor!

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