System Power Test (Optional Step)
At this point you will have all the core components of the system put together: motherboard, CPU, cooler, and memory. If all these parts are in working order, you can power up your system at this point and reach the BIOS. This
is an optional step that ensures your core components are all working as intended, as a faulty motherboard, processor, or memory module (or incorrect installation of any of these) will prevent the system from booting.
If you plan to test the system now, please read An important note about voltage under the "Power Supply Installation” step before continuing.
Take your power supply out of its packaging and place it fan-side-up on a flat, static-free surface like a table or cardboard box. Locate the 24-pin ATX power cable and connect it to the matching slot on the motherboard, oriented
so the tab on the cable and the notch on the power connector align. The cable will only fit one way into the socket. Press down with a considerable amount of force until the tab slots over the notch. Repeat the process for
the EPS 4-pin or 8-pin CPU power connectors, as applicable.
If your motherboard has a video port you can connect a screen to, you can jump to the next paragraph. If it does not, you will need to install your graphics card into the full-length PCI Express socket nearest to the CPU and connect
any required power cables as per the “Graphics Card Installation” section. The graphics card’s PCI slot face plate will overhang the edge of the motherboard when installed, so position accordingly. The card should stand upright.
Be careful not to let the GPU’s weight bend or break the PCI Express slot or the graphics card.
Connect your screen to an available video-out port. Take your power supply’s AC adapter and connect one end to the wall and the other to your power supply. If your PSU has an on-off switch, set it to the on position. On some motherboards
a diagnostic or power LED will light up indicating it is receiving power.
Some motherboards have a power button onboard, but if yours does not, find the front panel header connectors (usually in the corner furthest away from the CPU power connectors, sometimes color-coded). If you can’t find it through
inspection, check your motherboard’s manual. It will be laid out there for you. Use the tip of your screwdriver or other metallic object to bridge the two “POWER SW” pins. Don’t worry, this cannot electrocute you.
If all went to plan, you should hear the power supply kick on and see the CPU cooler fan spinning. On this first boot, the motherboard may need extra time to recognize its hardware configuration and set parameters appropriately,
so be patient if it takes a while or the system turns off and on a couple times. After a minute or two, you should see the BIOS logo or splash image appear on your screen, indicating a successful POST. You can connect a keyboard
to access and navigate the BIOS if you wish, but at this point we have a successful boot and can continue building the system. Flip off the power switch at the PSU, disconnect the power cables and graphics card if installed,
and ready your workspace for the computer case.