Start simple:

  • Power strip or outlet fault; try a different known-good outlet.
  • For desktops, check PSU switch, 24-pin and CPU 8-pin connections.
  • For laptops, test with battery removed (if possible) and adapter only.
  • Look for liquid damage or burnt smells near DC jack/VRMs.
  • Motherboard short from standoff or debris.

Need help? Check here: /services/repairs/

What it might be (likely causes)#

  • No AC or a tripped power path
    Dead outlet, tripped power strip, or a PSU rocker switch in the O position. On laptops, a failed charger or loose DC jack can present as “totally dead.”

  • PSU / adapter failure
    Desktops with aging PSUs may show no lights, no fans. Laptops with failing adapters won’t light the charge LED. If a battery still has some charge, it might briefly flicker and die.

  • Main power connectors not seated
    The 24‑pin ATX and 8‑pin (4+4) CPU EPS connectors must be fully clicked in. A loose CPU EPS often means absolutely nothing happens on power press.

  • Front‑panel switch or case wiring
    The PWR_SW lead can be miswired. Shorting the two power‑switch header pins with a screwdriver is a safe test on desktops.

  • Board short / standoff issue
    An extra standoff or a stray screw under the motherboard can short the board, preventing power‑on.

  • Catastrophic component fault
    Rare but real: shorted VRMs, damaged CPU, spilled liquid. Look and sniff for scorching near the DC jack or VRM heatsinks.

Background: basic boot/firmware mindset here: /posts/the-art-of-making-things-boot/ and aging‑hardware patterns: /posts/top-problems-10-year-old-pcs/

Things to check (quick, safe wins)#

  1. Verify power at the wall
    Plug a lamp or phone charger into the same outlet. If the power strip has a breaker, press reset. Try the PC directly in a wall outlet.

  2. PSU and rear switches (desktop)
    Flip the PSU rocker to I. Some PSUs have a self‑test button/LED—use it. If the PSU fan doesn’t twitch on self‑test, suspect the PSU.

  3. Minimal power‑on test (desktop)

    • Unplug everything except motherboard 24‑pin, CPU 8‑pin, and one stick of RAM.
    • Disconnect GPU and all drives.
    • Briefly short the PWR_SW header pins to see if fans start.
      If it powers on now, add components back one at a time.

  4. Reseat main power leads
    Firmly reseat the 24‑pin ATX and 8‑pin CPU EPS connectors until they click. Verify the GPU has its PCIe power leads connected if installed.

  5. Laptop power path
    Remove the battery (if removable) and try AC‑only. If there’s a tiny reset pinhole on the bottom, press it (EC reset). Try a known‑good charger of the correct wattage. Related battery/charger logic: /posts/why-is-my-laptop-battery-not-charging/

  6. Front‑panel switch sanity (desktop)
    Check the case’s front‑panel header against the motherboard manual. As a test, you can short the power pins with a screwdriver to simulate the button.

  7. Board outside the case (desktop)
    If you recently built or moved the PC, remove the motherboard and test on cardboard with only CPU + cooler, one RAM stick, and PSU. This eliminates standoff shorts.

  8. Signs of damage
    Look for liquid residue, corrosion, or burn marks near the DC jack (laptops) and around VRMs/chokes (desktops). If you smell ozone or see scorching, stop testing and seek service.

  9. Check for life indicators
    Any tiny LEDs on the board? Does the charger light up at the jack? No indicators often means upstream power (PSU/adapter/outlet). Some laptops show a brief LED flash for a failed power sequence—note patterns.

Prep and backup tips if you get it to power on again: /posts/prepare-for-computer-repair/ and for broader stability: /posts/speed-up-old-laptop/

Patterns that narrow the cause#

  • Absolutely no lights, no fans → wall/strip/PSU/adapter/DC jack.
  • Fans twitch then die → PSU protection tripping or board short.
  • Only powers on outside the case → standoff/short under the board.
  • Laptop runs on battery but not AC → charger or DC jack path.
  • Click from PSU, nothing else → overload/short; remove components and retry.

When to pause and get hands‑on help#

  • You find scorching, liquid damage, or a soft/loose DC jack.
  • The PSU clicks off immediately even with minimal load (possible short).
  • The power sequence is intermittent and unpredictable (cracked traces, failing VRMs).
    Bench testing with a lab PSU/charger and spare parts isolates the fault fast and safely.

Insight#

“Dead” systems are usually one broken link in the power path: wall → PSU/adapter → board regulators → components. Start at the wall and work inward, removing variables until something reacts. Once the supply is known good and the board isn’t shorted, the rest becomes a straightforward, almost boring, process of elimination.

Need a no‑nonsense diagnosis, PSU swap, or DC jack repair in Kirksville?
See /services/repairs/.