The Power Came Back and the Computer Didn't: What to Check First

The power blinks or drops for an hour. It comes back, the lights come on, the microwave is flashing — and the computer sits there. No fan, no light, nothing when you press the button. It is a genuinely bad feeling, because the machine is where the photos and the invoices and the tax returns live, and the obvious conclusion is that the outage killed the whole thing.

It usually did not. In our experience the drive and the data are almost always fine; what takes the hit is the part the electricity meets first. This guide is the triage in the order we would do it, and then the half of the topic that every "best battery backup" article skips: why a surge protector was never going to prevent this, what a UPS actually does differently, and the handful of setup mistakes that make an expensive one useless.

Two quick pointers so you are in the right place. If this is a laptop rather than a desktop, the fork is different and our laptop start-up triage covers it properly. If the tower lights up and runs but the screen stays black, that is a display problem, not a power one — start with our monitor guide. And if the machine works but restarts on its own while you are using it, or switches itself on in the middle of the night, those are separate articles linked at the bottom.

First question: is it the computer, or the thing it is plugged into?

Do not open anything yet. A large share of "dead after an outage" calls are not the computer at all — they are the strip on the floor behind the desk, and you can rule that in or out in two minutes.

Look at the surge protector itself. Most have a small breaker or reset button that pops out under a heavy load or a surge, and a lit indicator on the housing. Press the breaker back in if it is sticking out, and read the lights: nearly every surge protector has a "Protected" LED that tells you the protection circuit is still alive, and a "Grounded" one. If the Protected light is dark, the surge components inside have been used up. On some models the outlets keep working anyway — the strip has quietly become an ordinary extension lead — and on better ones an auto-shutoff kills the outlets entirely, which is exactly what a dead computer looks like from the outside.

Then take the strip out of the equation. Dell's own desktop power troubleshooting says to connect the machine directly to the wall outlet and to bypass any power regulators, meaning surge protectors, uninterruptible power supplies and splitters. Test the outlet with a lamp or a phone charger while you are there. If the computer comes to life plugged straight into the wall, you have found your fault and it costs about twenty dollars to fix.

The 30-second reset that revives a lot of dead desktops

If the wall outlet is good and the machine is still dead, do this next, because it costs nothing and it works more often than it has any right to. Small amounts of charge stay in a computer's circuitry after the cord comes out, and an abrupt power cut can leave that residue in a state where the board refuses to start.

Dell publishes the exact procedure for its desktops and all-in-ones, and the same idea applies broadly: turn the computer off, disconnect the power cable, unplug everything else — USB drives, printer cables, memory cards — then press and hold the power button for 30 to 35 seconds to drain residual power and reset the real-time clock. Reconnect the power cable and turn it on.

The timing detail matters more than people expect, and it is where the generic advice goes wrong. Dell states that the reset is aborted if you interrupt the power or hold the button for less than 30 seconds or more than 35. Every listicle says "hold it for ten seconds." Ten seconds drains the charge but does not perform the reset, so people try it, get nothing, and conclude the machine is dead. Count it out properly, once.

Still nothing? The power supply is the prime suspect — and it has a test button

In a desktop, the power supply is the metal box at the back that the wall cord plugs into, and it is the component that meets a surge or a hard cut before anything else does. When a tower is completely dead after an outage — no fan, no lights, no beeps — that is where we look first, and it is very often the answer.

There is a way to check it without any tools on many machines. Dell desktops have a built-in self-test button on the power supply itself: press it, and if the self-test LED turns on, the unit can still deliver power to the motherboard. If the light does not come on, it cannot. Other brands vary, but the principle is the same, and this is the one test that tells you whether to spend money on a diagnosis or just on a part.

One more thing worth a glance, especially on older or imported towers: some power supplies have a small red slide switch selecting 110 V or 220 V. If it has been knocked to the wrong setting the machine will not start (and on the wrong setting it can be damaged), so make sure it matches your region. Most modern supplies detect the voltage automatically and have no switch at all — if you do not see one, there is nothing to set.

The reassuring part: a power supply is one of the cheapest components in the machine and one of the most straightforward to swap. A dead one does not mean a dead computer, and it does not touch what is on the drive.

What about the files?

This is the question people actually want answered, so here it is plainly. If the machine will not power on at all, the drive has not been erased — it simply has not been given any electricity. Drives are usually recoverable from a dead computer, and if the fault is the power supply the storage was never involved.

What an abrupt cut can do is interrupt something mid-write, which is why a file you had open sometimes comes back stale or damaged even though everything else is fine. That is also the honest argument for a backup you do not have to think about, because a power cut is the least dramatic of the many things that can take a file away from you.

One specific thing to expect: if the computer does power up but stops at a blue screen asking for a BitLocker recovery key instead of loading Windows, do not panic and do not start reinstalling. That is an encryption prompt, not a broken machine, and the key is recoverable if it was saved to your Microsoft account. We cover that whole road separately.

The rest of the house came back in the wrong order

The other half of the post-outage call is everything that is not the computer. Modems, routers, printers, cameras, gate openers, mesh points and smart plugs all wake up at slightly different speeds and in no particular sequence, and devices that were happy for two years can come back confused because they booted before the thing they depend on.

The fix is usually order rather than repair. Power the modem up first and let it settle until its lights are steady, then the router, then everything else. Wireless printers are the classic straggler — they often come back on a different address and need a nudge before the computer can see them again. Far-end mesh nodes and the camera at the end of the driveway are the ones that come back last, or not at all, which is why "everything works except the camera at the gate" is such a common sentence the morning after.

Why the surge protector did not help

Here is the correction that matters most, and it catches out careful people who thought they had already handled this. A surge protector and a battery backup solve different problems, and the problem that damages computers around here is mostly the second one.

A surge protector deals with overvoltage — a spike, a transient, a jolt of excess voltage. Inside are components called metal oxide varistors that absorb the excess and divert it to ground. What it does not do, and cannot do, is anything about voltage going the other way or disappearing. A sag, a brownout or a full outage is a continuity problem, not a spike, and a surge strip has no way to produce power it is not being given. It will sit there through the dip that corrupts your file and the cut that stops your machine, doing precisely what it was designed to do, which is nothing.

The second thing about surge protectors is that they wear out, invisibly. Eaton, which makes the Tripp Lite surge protectors you see everywhere, describes the joule rating as a sponge: there is a limited absorption capacity, and once it is reached the unit can no longer protect and must be replaced. Accumulated damage from many small incidents, or one large one, degrades the varistors past the point of doing any good. Eaton suggests at least 1,000 joules for sensitive and costly equipment such as computers, televisions and audio-video gear.

The practical upshot is a habit rather than a purchase: read the Protected light occasionally, and replace the strip after any event big enough to make you think about it. A surge protector that has already taken a hit looks identical to a new one, powers your equipment identically, and protects it not at all. And a plain power strip — no joule rating printed on it, no indicator light — was never a surge protector in the first place, no matter how many outlets it has.

What a UPS actually does — and the four ways people set one up wrong

A UPS, an uninterruptible power supply, is a battery in a box that sits between the wall and your equipment. Power drops, the battery takes over within a fraction of a second, and the computer never knows anything happened. The obvious benefit is the few minutes to save your work and shut down properly. The bigger one, out here, is that it rides straight through the brief dip that is far more common than a real blackout.

There is a feature worth knowing the name of, because it is what separates the cheap units from the ones worth buying: automatic voltage regulation, found on what are called line-interactive models. Rather than switching to battery every time the voltage sags, an AVR unit boosts a low input or trims a high one back to a normal level using a transformer, so it corrects moderate brownouts and overvoltages without consuming any battery at all. On a summer afternoon when the whole neighbourhood's air conditioning is pulling at once, that is the difference between a UPS that quietly does its job for years and one that chews through its battery by August.

Now the setup mistakes, which are the reason plenty of people own a UPS that is not protecting them. One: only some of the outlets are battery-backed. APC is blunt about it — not all outlets provide backup power, so the vital equipment goes in the ones labelled Battery Backup and everything else goes in the surge-only outlets. People plug the computer into the wrong half constantly, and only find out during the next outage.

Two: nothing belongs between the UPS and the equipment. Schneider Electric, which owns APC, recommends against plugging any surge protector, power strip or extension cord into the output of a Back-UPS or Smart-UPS, and equally against feeding a UPS from a surge strip. Beyond the safety argument, a surge strip's filtering can mask part of the load so the UPS under-reports how much is plugged into it, which is how a unit ends up overloaded without anyone realising. Each box goes straight into a properly grounded wall outlet.

Three: size it with headroom, and understand that VA and watts are not the same number. VA is the capacity rating on the box; watts is what your equipment actually consumes; the ratio between them is the power factor. Add up the wattage of what is going on the battery outlets and leave room — APC recommends never loading a unit above 80 percent, so there is slack for the inrush when equipment first starts up. A typical desktop, one monitor, a modem and a router is comfortable on a mid-range home unit, and gets you the several minutes you need rather than several hours you do not.

Four, and this is the one nobody warns you about: some desktops shut down the instant the UPS takes over, which feels like a faulty UPS and is not. Computers with active power factor correction supplies — most decent modern ones — can fail to recognise the stepped, approximated waveform that budget units produce on battery. CyberPower describes the gap in that approximated wave as the cause, and the machine reads it as a power loss. If your PC drops the moment the lights flicker despite being on a battery backup, the answer is a unit that produces a true sine wave on battery, not a bigger one.

The one thing to plug in that nobody thinks of, and the one to keep off

Put the modem and the router on the battery outlets. It is the cheapest upgrade in this whole article and it changes the character of an outage: with the network up, a laptop or phone keeps working, the security camera stays online, and you can look up when the power is coming back. It also quietly prevents a category of service call — an enormous number of "our internet is down" reports at small businesses are really "our network hardware lost power and came back wrong."

And keep one thing off it entirely: a laser printer. APC recommends never battery-backing a laser printer, and says it should not go in the surge-only outlets of a UPS either; CyberPower says the same and will decline warranty service on a unit that failed with a laser printer attached. The warm-up draws a large inrush of current that can overload the UPS or fault it outright, and their guidance is that a laser printer is better on its own circuit with an ordinary surge protector. Inkjets are not the same problem, but a laser is genuinely capable of killing the thing you bought to protect everything else.

The Southern California version: most of our outages are announced days ahead

There is a local wrinkle that makes all of this more actionable here than it would be somewhere with ordinary storm outages. A large share of our planned interruptions are Public Safety Power Shutoffs — power switched off deliberately when strong winds, low humidity and dry vegetation make the lines a fire risk. Unlike a blackout, these come with notice.

If Southern California Edison is the name on your bill, the notification ladder is published: a weather dashboard showing potentially affected counties four to seven days out, then alerts as conditions are forecast around three days ahead, refined circuit lists two days and one day out, and a final notification one to four hours before power goes off. When the weather improves, crews have to inspect the lines before re-energising, and SCE says inspections typically take up to eight hours, longer if daylight is needed for ground or aerial patrols. So the realistic planning number is not "an hour or two" — it is most of a working day.

Worth saying plainly, because a lot of local advice gets this wrong: Edison is not everyone's utility here. Glendale, Pasadena, Riverside and Anaheim all run their own city-owned electric utilities, Los Angeles is served by LADWP, and much of the Coachella Valley is on the Imperial Irrigation District rather than Edison — with a boundary that does not follow city lines. Sign up for outage alerts with whoever actually sends you the bill, and add a second contact if there is a house that sits empty part of the year.

The advance notice is what turns a UPS from a gadget into a plan, because it means the single most protective thing you can do is free. Ready.gov's guidance for outages is to turn off or disconnect appliances, equipment and electronics, because power may return with momentary surges or spikes that can cause damage — and to leave one light on so you know the moment it is back. A computer that was shut down cleanly and unplugged before a scheduled shutoff is exposed to none of the restoration surge and none of the mid-write corruption.

The unannounced version is the summer one, and it is smaller and more frequent than people picture. On a 110-degree afternoon at peak load, it is the brief dip or flicker — the one that resets the microwave clock — rather than a long blackout that corrupts a drive, trips a machine mid-write, and leaves a desktop that will not come back. That is the exact event a UPS with voltage regulation absorbs completely and a surge strip ignores.

How we can help

If you have worked through the outlet, the strip, the 30-second reset and the supply's self-test and the machine is still dead, that is the natural stopping point for a home fix. Diagnosing and swapping a power supply is bench work, it is inexpensive, and it does not put your files at risk — and if it turns out to be something past the supply, we will tell you that before you spend anything, including getting the drive and its contents out safely.

We look after computers, networks and small-business setups across Southern California and the Coachella Valley, which means we spend a good part of every summer and every windy autumn on exactly this. We are happy to size a battery backup properly for what you actually have, wire the modem and router onto the battery side, keep the laser printer off it, and check whether the surge protectors around the house are still protecting anything. We do not sell hardware, so if the honest answer is that a thirty-dollar strip is all you need, that is what you will hear.