Lightning hit. Now your PC won't start, the screen's blank, or Windows is throwing a fit every ten minutes. A lightning strike PC situation ranges from a simple power-state glitch all the way to total hardware loss, and the only way to know which you're dealing with is to work through it methodically. This guide does exactly that.

What Causes Lightning Strike PC Damage?

Lightning doesn't need to hit your house directly to wreck your PC. A nearby strike induces a massive voltage surge across the power grid, and that surge travels straight down your mains cable into whatever is plugged in. If your surge protector's metal oxide varistors were already worn out (or it took a hit it couldn't handle), the full force of that spike reaches your hardware. The power supply usually takes the first hit, but the surge can punch through to the motherboard, GPU, and storage in the same instant.

The other common entry point is the Ethernet cable. Network cabling runs through walls and sometimes outside, and it acts like an antenna during a storm. A surge travelling through the Ethernet path bypasses your power strip entirely and goes straight into the motherboard's network controller. This is why you sometimes see a PC that boots fine but has a completely dead wired network port. The rest of the machine is untouched, but that one chip is gone.

Then there's the software side. Even if the hardware survives, an abrupt power loss mid-write can corrupt Windows system files, the boot configuration data (BCD), or the file system itself. The machine powers on, gets halfway through the Windows loading animation, and either blue-screens or hangs. That's not necessarily hardware damage. It can be file system corruption that DISM and SFC can actually fix.

Here's a rough breakdown of the main failure paths:

Power path damage: surge through mains cable hits the PSU, charger, or motherboard power circuitry.
Network path damage: surge through Ethernet or coaxial cable kills the network controller or router.
Windows corruption: abrupt shutdown during a write corrupts system files or boot data.
Storage and memory instability: partial electrical damage causes intermittent crashes, blue screens, or read errors.
Peripheral damage: monitor, dock, USB hub, or router takes the hit instead of (or as well as) the PC.

Knowing which path the surge took tells you where to look first. A PC that won't power on at all points squarely at the power path. A PC that boots but loses Ethernet points at the network path. A PC that crashes randomly after booting is more likely a software or storage problem, though partial hardware damage can look identical. Work through the tiers below in order.

Quick routeStart here

Lightning Strike PC: Quick Fix (Start Here)

Before anything else, check for physical danger. This isn't optional.

Stop immediately if you detect smoke, a burnt smell, melted plastic, sparks, or abnormal heat. Unplug the machine from the wall. Do not power it on again until you've ruled out physical damage. A machine that clicks repeatedly or shuts down the instant it powers on should not be cycled repeatedly.

Power Reset and Strip-Down Easy

Disconnect everything nonessential.
Unplug Ethernet, coaxial, telephone lines, USB devices, docks, printers, external drives, and any extra monitors. Leave only: the PC, the power cable, one monitor if needed, and a keyboard. You want to isolate the machine from every external path the surge could have used.
Do a full power reset.
Shut down the PC (if it's on). Unplug the AC power cable from the wall. If the machine has a removable battery, take it out. Hold the power button for 30 seconds. This drains residual charge from capacitors on the board and clears any stuck power state. Reconnect the power cable and try starting it.
Test a different wall outlet and cable.
Don't plug back into the same surge protector, especially if it was connected during the strike. Surge protectors sacrifice their internal components to protect yours, but they keep supplying power afterwards. A dead surge protector looks exactly like a working one from the outside. Use a different outlet and, if you have one, a known-good power cable.
Observe the exact symptom.
No lights, no fans at all: the power path is suspect (PSU, charger, or motherboard). Lights and fans spin but no display: test another monitor cable and input, then read on. Windows loads but crashes: skip to the intermediate section. Ethernet dead but Wi-Fi works: almost certainly a fried network port, covered below.

If the PC boots normally after the reset and strip-down, great. Don't reconnect everything at once. Add peripherals back one at a time to identify anything that's still damaged.

Intermediate routeKeep going if needed

Intermediate Lightning Strike PC Fixes

The machine powers on. Maybe it boots into Windows, maybe it gets stuck partway. Either way, the first thing you do before running any repair is back up your data. Not after. Before.

If the hard drive is making clicking sounds or Windows is throwing read errors, do not run any repairs. Minimise disk activity and consider professional data recovery. Every write to a failing drive risks overwriting recoverable data.

Back Up Data and Run Startup Repair Medium

Back up immediately.
If Windows loads, copy your critical files to an external drive or cloud storage right now. Don't skip this. Repairs can go wrong, and a drive that survived the surge might be running on borrowed time.
Try Windows Update first.
If the machine is stable enough, check for pending updates and install them, then do a clean restart. Sometimes a surge-induced corruption affects a driver or system component that an update replaces. It's a long shot, but it takes two minutes.
Use the Windows Recovery Environment if startup fails.
Hold Shift and click Restart (from the login screen or Start menu). Go to Troubleshoot, then Advanced options, then Startup Repair. Let it run. If Startup Repair can't fix it, go back and try System Restore to a point before the storm. Avoid 'Reset this PC' until your data is safely backed up, because a reset can wipe everything.
Check Device Manager for flagged hardware.
Right-click Start and open Device Manager. Look for yellow warning triangles under Network adapters, Display adapters, Storage controllers, and USB controllers. If the Ethernet adapter shows a fault, don't waste time reinstalling drivers on a physically damaged port. Plug in a USB-to-Ethernet adapter instead and test connectivity that way. For more detail on diagnosing a dead wired connection, that process is covered separately.
Run manufacturer pre-boot diagnostics.
Most PCs (Dell, HP, Lenovo, ASUS, etc.) have built-in hardware diagnostics accessible at startup, usually by pressing F2, F12, or Escape during the POST screen. Run the full diagnostic suite. Record any error codes. A failed memory, storage, or system board test is evidence of physical hardware damage that no Windows repair command can touch.

If Startup Repair or System Restore gets Windows loading cleanly and Device Manager shows no warnings, you're likely dealing with software corruption rather than hardware damage. Proceed to the advanced section to confirm the file system is healthy.

Advanced routeChange one thing at a time

Advanced Lightning Strike PC Repairs

This is where you sort out Windows corruption properly. These tools, DISM and SFC, are the right ones for the job when the hardware itself is intact but the OS took a hit from the abrupt power loss. Microsoft's own documentation on repairing a Windows image explains what these commands actually do under the hood, and it's useful reading if you want to understand why the order matters.

DISM and SFC Repair Advanced

Open Command Prompt as administrator.
Right-click Start, choose Windows Terminal (Admin) or Command Prompt (Admin). If Windows won't boot, access Command Prompt through the Recovery Environment: Troubleshoot, Advanced options, Command Prompt.
Run DISM first.
Type DISM.exe /Online /Cleanup-image /Restorehealth and press Enter. This contacts Windows Update to download clean copies of any corrupted system files. It can take 10 to 20 minutes. Let it finish completely before moving on. If it fails with an error about the source, you may need to point it at a Windows ISO using the /Source switch.
Run SFC after DISM completes.
Type sfc /scannow and press Enter. SFC uses the component store that DISM just repaired to replace any corrupted protected system files. If it reports 'Windows Resource Protection found corrupt files but was unable to fix some of them', check the CBS log at C:\Windows\Logs\CBS\CBS.log for specifics. This one often needs a second reboot before it sticks, so restart and run SFC again if the first pass reports failures.
Check the file system with chkdsk.
After backing up data, run chkdsk C: /scan to do a non-destructive scan. If it reports errors, schedule a fix with chkdsk C: /f and restart. Don't start with the /r flag on a drive you suspect is failing physically, as a full sector-by-sector scan on a damaged drive can take hours and stress it further.
Check Event Viewer for hardware errors.
Open Event Viewer (search for it in Start), go to Windows Logs, then System. Filter for Critical and Error events from around the time of the strike and since. Look specifically for WHEA-Logger entries (hardware errors), Disk errors (source: disk), display driver failures, and network adapter resets. WHEA errors in particular are a strong sign of physical hardware damage rather than software corruption.

If DISM and SFC both complete without errors, chkdsk finds nothing, and Event Viewer shows no WHEA or disk errors, the Windows side is clean. Monitor the machine for a few days before declaring it fully sorted.

Hardware Diagnostics and Component Replacement Advanced

Run full manufacturer diagnostics.
Use your PC maker's diagnostic suite to test memory, storage, the system board, network hardware, and the GPU if available. Dell uses SupportAssist (F12 at boot), HP uses HP PC Hardware Diagnostics (F2 or F4), Lenovo uses Lenovo Diagnostics. Run the extended tests, not the quick ones. Record every error code you see.
Interpret the results honestly.
A failed memory test means the RAM or memory controller is damaged. A failed storage test means the drive or its controller is gone. A failed system board test means the motherboard has physical damage. None of these failures can be fixed with DISM, SFC, a Windows reinstall, or a registry tweak. The component needs replacing.
Do not open the power supply.
If you suspect the PSU is dead, have it tested or replaced by a qualified technician. Capacitors inside a PSU can retain lethal voltage even after being unplugged for hours. This is not an exaggeration.
Replace or work around damaged components.
A dead Ethernet port on the motherboard: buy a USB-to-Ethernet adapter (around £10 to £15) and use that instead. A dead GPU: if the motherboard has integrated graphics, remove the discrete card and use the onboard output temporarily. A dead PSU: replace it with a unit of the same or higher wattage and the same connector set. For a PC that won't power on at all after a surge, the PSU is the first component to swap.

Do not modify the registry as a response to lightning damage. Registry edits cannot repair electrical damage and can make Windows unbootable. If you do make any deliberate registry change for another reason, export a backup first.

Preventing Lightning Strike PC Damage

The honest answer is that nothing guarantees protection from a direct or nearby lightning strike. But you can dramatically reduce the risk and the damage when it happens.

Priority one: unplug during storms. Physical disconnection is the only method that actually works every time. A surge protector can handle minor transients from the grid, but a real lightning-induced surge will overwhelm most consumer-grade units. As Tom's Hardware explains in their surge protector vs UPS breakdown, even a good surge protector has joule limits, and once those are consumed, the device offers no further protection. It doesn't tell you when that's happened.

Priority two: protect every entry point. Most people protect the mains cable and forget the Ethernet. If your broadband cable runs outside the house before entering, a surge can travel through it just as easily as through the power line. Use a surge-protected network switch or inline Ethernet surge protector, and make sure your router is also protected. Coaxial and telephone lines are the same story.

Priority three: use a UPS for anything critical. An uninterruptible power supply does two things: it conditions the incoming power (filtering minor surges and sags) and it keeps the machine running long enough to shut down cleanly if the power cuts out. That second function alone can prevent the file system corruption that causes half the post-lightning Windows problems. Look for a UPS with automatic voltage regulation (AVR) and software-controlled shutdown support.

Priority four: keep backups that aren't connected to the machine. An external drive sitting next to the PC will die in the same surge. A cloud backup or an offsite drive won't. If the hardware is a total loss, a good backup means you lose the machine but not the data. That's a recoverable situation. Losing both is not.

And replace any surge protector that took a significant hit, even if it still powers devices. The internal varistors are sacrificial. Once they're gone, you've got a very expensive extension lead. For guidance on choosing a replacement surge protector with adequate joule ratings for UK mains, that's covered in detail elsewhere on the site.

Lightning Strike PC: Summary

A lightning strike PC can fail in a dozen different ways, and the fix depends entirely on which part of the machine took the hit. Start safe, strip the machine back, and identify the exact symptom before touching anything else. If it powers on, back up your data before running any repair. DISM and SFC sort out Windows corruption. Manufacturer diagnostics tell you whether the hardware itself is gone. And if the diagnostics fail, no software fix in the world will change that outcome. The component needs replacing. Work through the tiers in order, don't skip to a Windows reinstall, and you'll either have it sorted or have a clear answer about what needs to go in the bin.

Lightning Strike PC: How to Diagnose and Fix the Damage