If your PC does not turn on anymore, try this
I'm not a hardware guy. While I'm capable of building a PC from scratch by selecting compatible components and putting it all together, I'm only interested in hardware when I'm about to build a new PC and not the other time of the year.
One of the first things I do each morning is to power on a PC. Imagine my surprise when my PC would not boot at all.
This guide provides you with tips that may help you fix the not turning on issue on your own. Please note though that it won't provide a 100% surefire way of fixing things as there is none.
Instead, we are going to take a look at basic diagnostic options that may help you understand what is happening. Often, it is a basic issue that is easily fixed even if you have no idea about components that computers use to function.
Inspection
Instead of panicking right away, take a look at your PC and the connected components. In particular, check the following:
- Do other electronic devices work. If power is out completely, those won't work as well.
- Check the power connection to the PC. Make sure the cable is not lose. Also, make sure the power connection is working by testing it with another electronic device.
- PCs have a power on/off switch on the back usually. Make sure the switch is in the on position.
- Check if the PC monitor has power, and that its connection to the PC is firm in place.
- Do you hear fans and the PC powering up when you turn it on?
- Check the power and reset buttons at the front. Do they appear stuck or out of place?
After inspecting the PC externally, it is time to open it up if the above suggestions do not fix the issue. While I'd suggest you turn off the power before you do so, you may get important clues why something is not working if you keep the power on for a moment longer. Just make sure you don't touch anything hardware related after you open the PC while it is turned on.
Open the left side of the PC panel. You may need a screwdriver for this or can use your hands to do so depending on the case used.
The motherboard indicates with an LED light usually if it gets power. If you don't see any light there, it can mean that cables are not connected properly anymore, or that the power supply or motherboard are dead.
Try hitting the on switch again. Do you hear fans starting to work inside the PC? Or beeping sounds that come from the internal speaker system?
If you hear fans starting, you know that the motherboard is getting power. Beeping sounds indicate issues and you can check out the codes here on this page.
Please remove the power connector from the PC and switch the power supply state to off before you continue.
Once you have done so, it is time to check the connecting cables. As far as components are concerned, the most important ones are the power supply unit at the back that supplies power to the system, the motherboard, the processor, the video card, and memory.
I suggest you check all cables and make sure they are firmly in place. If you notice a lose cable, it may very well be the reason why the PC did not turn on.
Also, check that memory and the video card are connected properly.
The power on button was stuck on the PC that would not boot this morning. All I had to do was put it in the right place to have the system boot up again without any further issues.
Once you are done with the checking, plug the power cord back in and flip the power switch back to on. Try starting the PC and monitor what is happening.
What if those methods did not fix the issue?
One thing you can try is remove any component that is not required to run the PC. This means external devices, all but one memory module, internal cards (not the video card obviously).
Best option here is to remove everything at once, and remember where each component went, to see if the PC starts up afterwards. If it does, add each component one by one to the machine again and test if it caused the issue.
If that does not work, then you may want to test other components if you have them around. You may not have a spare power supply unit, motherboard or cpu though, and even if you do, may not be comfortable testing the system on your own.
Your best bet then is to ask a friend for help if you know someone who is proficient in these things, or take your PC to a repair shop to get it looked at there.
When i shutdown my pc and unplug it, i was curious that i off the power supply in my cpu and change it to 115V from 230V and I hear a click noise and i immediately turn it back to 230V. Next day, i turn on my pc it works fine and then suddenly when i left it, it immediately turn black as in no lights or fan working, so I immediately open it, and then when im opening it, now it doesn’t work
Busted! I use the motherboard insulating washers to protect the motherboard from getting scratched by the screws. I guess I’ll have to remove them now, but my question is why are these things sold in the first place if they can cause problems?
Just wished to share what worked for me!
The motherboard would light up meaning no issue with the power cable and unit. However, my CPU wouldn’t turn on.
I tried holding the power button pressed for 1 minute while power cable removed but no avail.
The issue was with the CMOS. I removed the battery using a flathead, checked the voltage and it seemed slightly down (2.5V instead of 3V). However, just putting it back after wiping seemed to work. But I need to get a new battery as I can notice my date resetting now and then.
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Hey I had a similar problem – PC would not boot. No power at all, no fans LEDS or beeps. I swapped out the PSU and the PC worked fine for a couple of weeks. In the intervening period I tested the PSU I previously removed with a multimeter, cleaned it up and it checked out OK. So when the PC failed again I tested it with the PSU I originally removed and it powered up. Reconnected the installed PSU and it powered up. ? What the hell? Reading this thread I’m now thinking that the CMOS battery could be the culprit.
If it was the CMOS battery then wouldn’t the CMOS clear. All the settings are still retained. I suppose I could pull the battery and test it or just replace it and hope for the best but the PC is inside my desk and its a pain to get at. (CPU Temps etc are very stable BTW).
I have enccountered a wierd problem.
Some time ago I removed the power cable from me pc when I was on vecation.
When I came back the pc wouldent power on. I have a button on the backside witch sais CMOS, and it was pulsating with a blue light. I tested the psu by hardwireing it, and the fans started running. I removed every cable and part, and put it back together. Nothing worked. After a while (several hours) the button on the back side stopped blinking, and the pc would power on again. I did the same mistake again, and cut the power while on vecation, but now the CMOS button wont stop blinking. I also replacced the CR25 battery with a new one. Anyone has an idea of what is cousing the problem?
PSU testers run about $10.
Good to have one on hand.
Order one when you order that spare PSU you saw on sale.
…computer not POSTing is pretty easy to diag:
– Is the power led burning on the motherboard (Asus has always a green led on the motherboard that is on when there is power, even if the computer is off). If it’s off, time for a new motherboard or power supply.
– Remove all power cables from anything but the motherboard.
– Remove front panel connectors and use the guide to “short” momentarily the pins for the power button. It should start spinning the fans. As those pins are (almost) directly forwarded to the PSU, if it starts the fans, the PSU is outputting power, if it stops spinning soon after, it means the Motherboard is not picking up a “power good” signal from the PSU or there is a problem with the motherboard/videocard to get past the POST.
Another funny thing i’ve seen a long time ago :
There was blown up capacitors on the mb (on a old motherboard which had a Pentium 3 on it), and they were causing random reboots.
Random reboots were happening more and more often with weeks passing by, and at first i noticed it was linked to the pc’s activity. If it was staying idle for say 5mn, it would reboot, so as a temporary workaround i was leaving a defrag utility running when i was afk to keep it busy ;D
At some point i just replaced the mb.
Loose! Jebsus.
I had this happen to me once a few years ago. It turns out my power supply died. It was the first time I’ve ever had a computer outlast the PSU. It never occurred to me that PSUs die so it took me 3 days of head scratching to diagnose what the problem was.
Hey Martin,
Good tips, glad you found the button problem. Being somewhat of a hardware guy, I would suggest a few more diagnostics, but before I do, let’s address your case power switch. If it’s a piston-type of arrangement (most newer ones are) and it’s just sticky, it will only get worse. Replace it (applies mostly to brand cases like Dell, etc.), or, if the case was relatively inexpensive, here’s your excuse to go case shopping! Case power switch failures are the type of hardware that normally shows either DOA from day one, or intermittent after years of use. Silicon type sprays usually don’t help a sticky piston switch, they are too well sealed. In an emergency, I have disconnected the two wire (two pin) connector on the Motherboard and placed a jumper cap over those two pins, connecting them (they are usually a simple +5vdc/-5vdc arrangement). Use a power switch downstream (likely on the power supply) until a replacement is procured.
Additional info: This is going to sound so OSHUA to y’all, but seriously, before touching MB components, like making sure RAM and PCI cards are “fitted” snugly, grab one of those static discharge wrist bands and fasten the wire (usually on an alligator clip) to a metal piece of the case. They are cheap, and two or three of them should be in the same place you keep the screw-driver and/or pliers you fetch when you open the case.
Some older MB’s have CMOS set-ups that will actually prevent power-up when the CMOS has no power at all… Meaning the battery is dead. I’ve sat there with a multi-meter, checking the power supply inputs and outputs, motherboard LED, on and on, scratching my head because everything is checking out… Only to find a dead motherboard battery preventing power-on. CR-25 is burned into my brain. If you work on these things long enough, you know to keep a CR-25 battery (new, in it’s sealed package) in your tool kit. New in the package (surrounded by plastic) I’ve had them last 5+ years in my tool-kit and still able to save the day when needed.
A comment by Thomas here is also spot on. Pull the power cable from the power supply, and keep the power supply switch in the “on” position for a minute or so. You want to discharge the capacitors. You can quick check this with the multi-meter without even opening up the power supply, just touch the two meter probes to any two metal prongs on the power supply where the cable was plugged in. You want zero reading in either DC voltage or DC amperage.
Want to know the most bizzare thing? The first time I saw this, I thought it was so bizzare that I’d never see it again… But I’ve run across it with many custom-built rigs by gamers: You spent a couple hundred dollars on a motherboard. It’s very cool looking. You are very particular and build your system just so. Ever notice those little dots that are around the holes in the motherboard where you put the screws to fasten it to the case? Ever notice that different holes have a different number of little dots around them? Ever worry that by tightening a screw down on those little dots they may get scratched and ruin your “pristine” MB?
I had a client who went and found special plastic washers to put on his motherboard screws so that no damage would occur. Darn thing would power on, then off. Then not at all. Then on again for maybe a hour or a day, then off again. It took me FOREVER to figure that one out. Those little “dots” are circuit ground points! They are there so that the motherboard screw-head contacts them directly and provides the ground connection to the case! They are MEANT to get scratched by the head of the screw (makes for good contact). By placing plastic washers in there, this client created an intermittent problem the likes of which I had never seen. I laughed. I thought sure I’d never encounter that again.
I was wrong – Ha! I’ve seen it twice more. Now I ALWAYS look at the motherboard screws!
Regards,
Mr. Joey
Thanks for the good advice,
Martin and Mr.Joey!
Q:
==
Any way/app/utility in LINUX
to measure the voltage of the MB CMOS battery,
without opening the PC…?.
(that would save a LOT of guessing/time…).
Disclaimer: I’m NOT a Hardware guy
but would only open up my DELL 745 Desktop,
if I knew the CMOS bat. was depleted…
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What’s old is new again!
I’m referring to your question, trek100. We wondered about this back in 1981. Here’s the problem, when your system is powered up, your motherboard supplies the power to the CMOS circuit. The battery only comes into play when your machine is powered off… Even then, the CMOS only draws a very small amount of current to keep the SRAM alive. That’s why, from the very beginning (set the way back machine to 1981) we figured a lithium battery, like the CR025, could probably keep the CMOS alive for 2-3 years… It would only have to do this when the machine is powered off, so even if that were half the time, you’d be looking at a lifespan of 4-6 years.
Turns out, I’ve seen 10 year old motherboards still working with the original battery. Since the motherboard kicks in power to the CMOS even before BIOS POST, there’s no way to get a reading from it when the system has power.
But I hecka like your thought process!
I suppose you could engineer something at the hardware level whereby a running and powered system could somehow cut power to the CMOS, thus flipping it to battery back-up, and take a reading, report this to the user, and then set power back on to the CMOS. I’ve never run into a MB capable of this. The cost to engineer it would probably be out of line…
Interesting thought.
Mr. Joey
@ Joey Spinoza:
I have no idea what OSHUA stands for (and neither, it seems, does the Internet). Did you mean to type OSHA, as in Occupational Safety and Health Administration?
On the merits, I’ve built several computers from scratch, and repaired a bunch more (both towers and laptops). I’ve had two computers that wouldn’t start at all because critical fans had died, in one case a CPU fan (which BIOS beeps, once decoded, tipped me off to), and in the other a northbridge fan (which I don’t remember how I figured out — it might have been BIOS beeps as well). The CPU fan was proprietary and “chipped” — thanks, Dell! — and replacing the northbridge fan required doing a juryrigged install of a generic fan, with the help of a Dremel and a pop-riveter. In another case, it was defective capacitors that had finally leaked too much (the same Dell!). No beeps there, I believe; the computer was just dead. And in another case, on a laptop, the jack for the AC/DC adapter had broken internally (a very inexpensive repair in terms of financial outlay, but an extremely time-consuming one). Actually, going way, way back to my very first laptop, a Zenith Z-180 with 640KB of RAM and a massive 20MB hard drive ;-), the internal AC power adapter eventually burned out and I had to rig an external power adapter to connect to the battery jack. (I got a total of 14 years of good use out of the Zenith; they don’t make ’em like they used to.)
Long story short, based on my limited experience alone, there can be lots of reasons a computer won’t start. This is a no-brainer, but if the computer in question is a tower, make sure the power supply’s switch didn’t accidentally get turned off, and if your boot/system drive is in a mobile drive rack, make sure the rack’s power switch didn’t accidentally get turned off. (Yes, I know, in the latter case, the system will start and POST, but it won’t boot.) Both have happened to people I know, after they had been rummaging around for something in the vicinity of the case.
Good catch… How that “U” got into OSHA, I haven’t a clue! Thanks.
Yes, there are a million stories in the city. I was just offering a starting point. However, after 30+ years in this, looking at the big picture, a computer that won’t power on, or one that spontaneously powers off, tends to be power supply related, probably half the time. Everything else you mentioned is entirely valid. I’ve seen lots of fan failures, exploding caps on the motherboard (especially around over-heated north and south bridges), on and on. Fortunately, power supplies are usually well labeled and you can open one up and with a simple inexpensive multi-meter check all the inputs and outputs pretty quickly.
Good thoughts,
Mr. Joey
Hi, thanks for the tips and additional information, that’s why I like my site so much, ha ;)
Good point about the CMOS battery, but it is quite difficult to find out I guess if you don’t have a replacement battery or meter.
I will monitor the power button for now.
One other tid-bit to go along with the motherboard screws… Those dots, those circuit ground points, are also why you NEED to use a screw (and it’s anchor) for EVERY hole your motherboard has to the chassis. If you leave one out, those dots/circuits aren’t making proper ground potential, this will show up in the weirdest ways somewhere down the line. To reiterate, ALWAYS look at the motherboard screws.
Mr. Joey
One of the things that helped me several times as an IT support worker is to unplug the power cable and keep the power button pressed for at least 30 sec. After that plug the cable again and boot normally.
I think it have something to do with the discharge of the capacitors but I’m no electronic expert..
thanks dude it worked saved me la lot of panic
First thing I try with a laptop that won’t turn on. Pop the battery and hold the powerbutton for a while. Plug in and it should fire back up!
So did you get the PC working? What was the problem? Don’t leave us hanging!
I never turn my PC off. It runs 365 X 24. PC’s are so power efficient that it doesn’t use that much extra power to keep it running. And warming up a cold PC puts a lot of stress on the electric components.
Power efficient? Then why do most desktop PC’s need a PSU of 500W or bigger? 500W, that’s like having all the light bulbs in the house turned on!
There’s only one computing device that can be left on 365/24 with minimum power consumption, and that is a regular laptop that maxes 65W power consumption!
A 500 watt power supply doesn’t pull 500 watts just from being on. If your parts are energy efficient, and consume only 40 watts, that’s what the power supply will give them, with some loss due to power supply inefficiency. So, ~50 to 60 watts would be used in a desktop with an SSD, AMD 5350 quad core, and 8 GB of RAM depending on the PS rating.
500 Wats or more? Only gaming rigs and only when GPU has some serious job to do (=when you are playing). If you are reading ghacks.net GPU is almost idle and its power consumption is at very, very low level.
I was a stuck power switch that prevented it from booting. I mentioned that in the guide ;)
Any of you guys familiar with a digital multi meter? If the answer is yes first hurdle cleared. Test for continuity point to point. Refer to schematics for the specs. Even if there’s not enough power it will fail to boot. Its quite a process. I’m glad we have solid state drives instead of waiting I’m gonna have a look over the one I’m working on. I just installed new RAM and it wouldn’t start. Its a wiring problem probably. be patient it can be sorted out methodically.
Or you had a electrical outage in your location that could’ve also triggered the switch and have seen this happen over the years with certain PSU but not all.