How to Plug In a Computer: Step-by-Step First-Time Setup
Quick answer / TL;DR: Plug in a computer in this order: PSU rocker switch to off, C13 power cord from the outlet (ideally a surge protector) into the C14 case inlet, then monitor power and video cable, then network and peripherals, and only then flip the PSU switch on and press the power button.
Plugging in a computer for the first time – a new build, a refurbished unit, a move to a new office – sounds trivial until you are holding the PSU rocker switch, a C13 cord, a monitor brick and a tangle of video cables, wondering what order to do it in.
The order exists for a reason: it keeps voltages off the internal cables while you connect, and it protects the PSU from a surprise load at switch-on. Follow these steps and the machine powers up cleanly.
Before the First Plug: the PSU Switch
Find the rocker switch on the back of the case next to the power inlet. It has an I (on) and O (off) mark. Set it to O before connecting anything. This keeps the PSU unenergized while you work, so no internal cable can carry voltage while it is being plugged in.
Step 1: Wall Side – Grounded Outlet and Surge Protection
Plug the surge-protected strip or outlet protector into the wall first, and the computer power cord into the surge device. Confirm the outlet is grounded – a three-hole receptacle with the earth pin intact. Do not chain surge protectors, and do not run the cord through a dimmer or a worn adapter.
Step 2: Case Side – the C13 into the C14 Inlet
With the PSU switch off, seat the C13 plug fully into the C14 inlet. A correct fit has no gap at the base and no wiggle. If the plug does not seat, stop and inspect for a bent earth pin – never force it, since a forced C13 arc-damages both the plug and the receptacle springs.
Step 3: Monitor, Video, Network, Peripherals
| Order | Connect | Check |
|---|
| 1 | Monitor power cord to its own surge outlet | Inlet type C7 or C13 matches |
| 2 | Video cable (HDMI or DisplayPort) GPU to monitor | GPU port, not the motherboard port, for a discrete card |
| 3 | Ethernet cable to the router | Link lights on both ends |
| 4 | Keyboard, mouse, USB devices | Any USB port |
| 5 | PSU switch to I, then the case power button | Fans spin, monitor wakes |
C13 cords, monitor power cords, HDMI, DisplayPort and Ethernet cables for the full first-time setup are stocked in matching lengths; see the catalog for the complete first-wiring kit list.
Common First-Plug Mistakes
- Plugging the power cord in with the PSU switch already on – the exact thing to avoid
- Using the motherboard HDMI port while a discrete GPU is installed – the monitor stays black
- Habit: pulling the C13 plug by the cord instead of gripping the plug body, which fatigues the inlet
- Skipping surge protection because the office already has a UPS on another circuit
Real-World Applications
New build desk: switch off, surge strip, C13 in, HDMI from the GPU, Ethernet, switch on – ten minutes top. IT deployment: the same order on forty desks, with the C13 and HDMI lengths pre-cut per floor plan. Refurb acceptance: first-plug testing with a bench PSU switch lockout catches inlet damage before the unit ships.
Related reading: The full cable inventory for the desk — computer-cord-guide
Related reading: Every port on the case, explained — what-plugs-into-a-computer
Frequently Asked Questions
What is the correct order to plug in a computer for the first time?
Set the PSU rocker switch to off, connect the surge protector to the wall and the C13 power cord to the case, then connect the monitor power and video cable, Ethernet, and USB peripherals, and only then flip the PSU switch on and press the power button.
Should the power switch be on or off when I connect the power cord?
Off. Connecting the cord with the PSU energized means voltage appears on the internal cables the moment the plug seats. Keeping the switch off during connection is the standard safe procedure, and it costs nothing.
Why is my monitor black after plugging everything in?
Most often the video cable is in the motherboard port instead of the discrete GPU port, or the monitor is on the wrong input. Confirm the cable enters the GPU, select the matching input on the monitor, and check that the PSU switch is actually on.
Do I need surge protection to plug in a computer?
It is strongly recommended, especially for towers with a desktop plus monitor on the same circuit. Plug the computer and monitor into a surge-protected strip rather than the wall directly; it is the cheapest protection against the spikes that do most PSU damage.
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