You hit the power button and nothing happens. No fans, no lights, no beep. It feels catastrophic. It usually isn’t. Work through these in order and stop when it springs back to life.
1. Rule out the wall
Sounds insulting. Fixes a surprising number of “dead” PCs.
- Try a different wall outlet — ideally one you know works.
- Bypass the surge protector or extension lead entirely; plug straight into the wall.
- Check the switch on the back of the power supply is set to
I, notO. - Swap the kettle lead if you have a spare. They fail more often than you’d think.
2. Look for any sign of life
Press power and watch closely for one second:
- Fans twitch and stop? That’s a short or a power-delivery fault — go to step 4.
- Motherboard LED is lit but nothing happens on button press? Suspect the front-panel power button or its header.
- Total darkness, no LEDs anywhere? Focus on the PSU and its connections — step 3.
3. Reseat the power connections
Power off at the wall first. Then, firmly re-seat:
- The 24-pin motherboard connector (it’s stiff — push until it clicks).
- The 8-pin (or 4+4) CPU power connector at the top of the board. This is the number one cause of no-boot after a build or a move. It’s easy to leave half-clipped.
- The PCIe power cables into the graphics card.
- Both ends of any modular cables at the PSU side.
Reconnect the wall, try again.
4. Strip it back
Disconnect everything non-essential and test with the bare minimum: motherboard, CPU + cooler, one stick of RAM, and either the CPU’s built-in graphics or the GPU.
- Remove extra RAM sticks — test with one, in the slot your manual specifies (usually A2).
- Unplug extra drives and case fans.
- Pull the graphics card if the CPU has integrated graphics.
If it boots now, add parts back one at a time until it fails again. The last thing you added is your culprit.
5. Clear CMOS
A bad BIOS setting or a failed overclock can stop a POST cold.
- Power off at the wall.
- Use the Clear CMOS button or jumper (check your motherboard manual), or remove the coin cell battery for five minutes.
- Reassemble and try again.
6. The paperclip test (PSU check)
If there’s still zero response, test whether the PSU turns on at all: with everything unplugged, bridge the green wire and any black wire on the 24-pin with a paperclip, then flip the PSU switch. Fans should spin. If they don’t, the power supply is dead — and that’s often good news, because it’s a cheap fix and usually doesn’t take other parts with it.
If you’re not comfortable with the paperclip test, skip it. It’s safe when done right but there’s no shame in bringing it to someone.
When to stop and get a second opinion
- You smell burning or see scorch marks — stop now, unplug it.
- Fans spin but you get no display and no beep/LED codes after step 4.
- It boots, then dies after a few seconds or minutes, repeatedly.
Those point to a motherboard, CPU, or PSU fault. Before you start buying replacement parts, get someone with a spare PSU and a spare stick of RAM to help you swap-test — it’s the fastest way to isolate which one actually failed.