HELP: PC Won't Turn On

[plamy1969]

Hi,
My PC issue started a year ago: after Sleep or Shutdown the fans and lights remained active, i.e. don't turn off. Otherwise Windows 11 stops and the monitor goes blank as well. So I had to switch off the button of the power supply on the rear or to press the front power button for few seconds until everything stops. Since that time I had to run the system via power on, i.e. starting the PC, no more "wake".
Few months ago until now the problem went bigger: the PC simply doesn't start after pressing the power button!!!
Sometimes it starts every day during 1-2 weeks, sometimes it doesn't during 4-5 days. I disconnect it from the electricity for hours with power supply button on or off - that doesn't help. Sometimes the PC starts successfully and once running, everything is just fine as if as no any problem exists. Until Sleep or Shutdown, then not starting again.
Not sure if the power supply or the motherboard are the problem because when the PC is connected to the electricity, (even not able to start) the light diode on the motherboard is lit.
I've searched for solution everywhere and still no any idea how to solve this terrible issue. Removing and reseating RAM, HDD, etc. doesn't help too.
The power options, drivers, etc. are all ok, never played with them actually. So they are not the reason. I think the reason may be hardware. A friend advised me to disable the internal graphics card from the BIOS, no effect. Don't know what to do anymore.
Please for your help!

 

[DarkDreams]

Have you tried shorting the powerpins on the motherboard manually? It could simply be the power button of the case that is starting to fail.

 

[Waldorf]

@plamy1969
might wanna add your system info to your profile, so folks can actually see your hw and dont have to guess, make sure t tick the box "visible to others".

remove power plug, remove cmos battery, press and hold power-on button for about 10s, then leave sitting for 2h.
insert battery, plug back in, power up and reset bios to defaults, reboot, then change/tweak, turning OFF any standby/sleep related options, as well as FAST BOOT for ram.

dont use standby/sleep/hibernation, makes ZERO sense on a non-mobile pc.
for short periods your away just leave it running, as even shutdown/new boot will put more "stress" on the parts (current rush etc), and if its more than 20-30 min (lunch etc), just shut it down.

if thats not doing it, try a different psu to rule it out.

 

[Bill_Bright]

@plamy1969 - since EVERYTHING inside your computer case depends on good, clean, stable power, your first step is make sure you are supplying it. Assuming all your cables are securely fastened now (and a loose cable is not the problem) you need to swap in a known good PSU to see what happens. If the problem remains, at least at that point, you have eliminated the PSU.

Note that lit LED on your motherboard most likely simply indicates the power supply is doing its job and supplying the required +5Vsb voltage. However, check your motherboard userguide. That is a status indicator LED and some boards use multiple LEDs, or will change colors to indicate a specific status. Make sure you understand what that lit LED on your board means.

And yes, please fill out your TPU System Specs so we understand what hardware we are dealing with.

dont use standby/sleep/hibernation, makes ZERO sense on a non-mobile pc.

Come on, Waldorf! This is total nonsense. Please get with the times, Waldorf. You are living 30 years in the past.

Proof? The following comment,

and if its more than 20-30 min (lunch etc), just shut it down.

As just about everyone on the planet knows, ever since the ATX Form Factor standard was launched in 1996 and became the industry standard for PCs and PC power supplies, when you "shut down" a PC, you are NOT removing power. Instead you ARE putting it in standby. And that has been working great for nearly 3 decades now.

By design and requirement, all ATX PSUs MUST maintain +5Vsb standby voltage AT ALL TIMES across multiple points on the motherboard, including system RAM, USB ports, NICs, and elsewhere when the computer is "shutdown".

The front panel power switch is merely a remote switch that dumps that +5Vsb voltage on the startup pin, signaling the chipset to tell the PSU to fully start. Without that +5Vsb voltage present the power button would not work! You could not wake the computer with a keyboard press or mouse wiggle, or remotely via the network.

The ONLY way to totally remove all power and take the computer totally out of standby mode is to either unplug the computer from the wall, or (if it has one) flip the master power switch on the back of the PSU to the "Off" or "0" position. Otherwise, when plugged in and that switch is set to "On" or "|", the computer is in a standby mode.

And for the record, allowing our computers to go into sleep mode, especially with modern versions of Windows makes perfect sense because Windows and our security programs are then able to keep themselves updated during those times we are not using the computer. That's a good thing because keeping the OS and security updated is a key step in keeping our computers secure.

remove power plug, remove cmos battery, press and hold power-on button for about 10s, then leave sitting for 2h.

As noted many times before to you Waldorf, this too is simply wrong. The case front panel power button is tied to a "momentary" circuit on the motherboard. It is isolated from the power supply. As soon as you press the button, the contact is sensed and all further contact is ignored, until the button is released and pressed again. All holding the button down does is tire the finger. It does NOT bleed or decay any residual voltages.

Leaving the computer unplugged and turned off for 2 hours just wastes 2 hours of time. Unless damaged, all computer power supplies have bleeder circuits to almost instantly discharge the AC input filter caps to safe levels. Even if that bleeder circuit is damaged, the power cord is unplugged! There is no AC flowing, therefore there is no DC output.

 

[plamy1969]

Thanks for all the advices above! But most of them would help if the PC doesn't turn on always. Actually, it turns on sometimes as it should. So this is an electronics - work or doesn't work. How is it possible sometimes to turn on if the power button is not ok, or the BIOS needs to be reset, or even the Power supply?!? That's what makes me confused.

 

[eidairaman1]

In that situation i'd gut the system and put all components on a non conductive table and elevate the motherboard so a gpu can be inserted correctly, that would cut the case out of the equation.

Also might be the power supply, your surge protector or the outlet itself. Make sure the power supply cord going into the psu is not loose, make sure it is not loose going into the outlet.

Possible chance the case power switch could be going bad, go pick 1 up, or move the reset switch plug to the power pins.

 

[Bill_Bright]

So this is an electronics - work or doesn't work. How is it possible sometimes to turn on if the power button is not ok

Because, sadly, "intermittent" is a third option with electronics, and the most difficult to troubleshoot when you cannot duplicate the problem on-demand. So again, swapping in a known good PSU, even if just to eliminate that from the equation, would be my suggestion.

Possible chance the case power switch could be going bad, go pick 1 up.

I agree this is possible as @DarkDreams also suggested above. Shorting the two pins on the motherboard the front panel switch's wires connect to does the same thing as pressing the switch. But this would be a hassle to do every time you need to boot or wake the computer.

Sadly, odds are you will not be able to find an exact replacement switch that fits your case. HOWEVER, if your case has a Reset button, you can simply pull the reset wires from the 2 pins on the mother and move them to the two pins used by the power switch, then just use the Reset button from now on. You will not longer have the reset option, except by going through the Start menu.

Side note - for those who frequently work with computer hardware and don't like the thought of sticking a highly conductive, metal screwdriver into the heart of live electronics, consider getting a motherboard power switch. These are particularly nice if you don't have rock-steady hands, 20/20 vision, and excellent lighting.

 

[Ruru]

Like said above, would be hella helpful if OP would tell about the hardware he/she is having problems with.

 

[Waldorf]

@plamy1969
again, you want help, pls fill out info.
beside, for troubleshooting, testing even unlikely causes , will at least allow us to exclude them, and narrow down where its stemming from.

you want help, and for that, it includes doing what ppl ask you to do, since they spend their time trying to help.

 

[eidairaman1]

Because, sadly, "intermittent" is a third option with electronics, and the most difficult to troubleshoot when you cannot duplicate the problem on-demand. So again, swapping in a known good PSU, even if just to eliminate that from the equation, would be my suggestion.


I agree this is possible as @DarkDreams also suggested above. Shorting the two pins on the motherboard the front panel switch's wires connect to does the same thing as pressing the switch. But this would be a hassle to do every time you need to boot or wake the computer.

Sadly, odds are you will not be able to find an exact replacement switch that fits your case. HOWEVER, if your case has a Reset button, you can simply pull the reset wires from the 2 pins on the mother and move them to the two pins used by the power switch, then just use the Reset button from now on. You will not longer have the reset option, except by going through the Start menu.

Side note - for those who frequently work with computer hardware and don't like the thought of sticking a highly conductive, metal screwdriver into the heart of live electronics, consider getting a motherboard power switch. These are particularly nice if you don't have rock-steady hands, 20/20 vision, and excellent lighting.

I don't like doing it that way either due to stray arc's.

 

[Bill_Bright]

I don't like doing it that way either due to stray arc's.

Well, with such low-voltage DC, I am not really worried about arcs (except potential ESD from my fingertips), or shorting anything out. My bigger concern is my hands aren't as steady as they used to be and flat tip screwdrivers are typically made of hardened steel and have sharp edges, easily capable of cutting through a circuit trace if not careful.

I keep one of the motherboard power switches on my bench, and in the tool bag in my truck to take on service calls. Sadly, you still need a steady hand, good eyes and good lighting to attach them - but at least it is a one-time task.

 

[eidairaman1]

Well, with such low-voltage DC, I am not really worried about arcs (except potential ESD from my fingertips), or shorting anything out. My bigger concern is my hands aren't as steady as they used to be and flat tip screwdrivers are typically made of hardened steel and have sharp edges, easily capable of cutting through a circuit trace if not careful.

I keep one of the motherboard power switches on my bench, and in the tool bag in my truck to take on service calls. Sadly, you still need a steady hand, good eyes and good lighting to attach them - but at least it is a one-time task.

I've killed usb storage drives via esd while a system was on, thank goodness it didn't kill the port/motherboard.

Being an A&P I treat my parts I overhaul like a baby. Yes a screwdriver can cut or puncture flesh if not used correctly. I just think about potential damage from stray arcs hitting nearby pins or components, and yes they act like a knife or scribe on firm surfaces.

 

[Bill_Bright]

I've killed usb storage drives via esd

The problem with ESD is the discharge can be so tiny we mere humans cannot see, hear or feel that a discharge even happened, yet that arcs can torch a Grand Canyon sized (microscopically speaking) scorched trench through millions of transistor gates.

Because they can be so tiny, I cannot be certain, but I believe I have killed several flash drives from ESD just from pulling them out of my pocket. Just another reason to make sure you put the cap back on them.

 

[Waldorf]

any home improvement/auto parts/online stores will have 12V buttons with on/off button in similar size to most case ones,
replaced a faulty one with a push button, only needed to use an open scissor to increase diameter of the existing opening,
and cut the wire behind the old switch to re-use.
looks even better than the stock one.

push switch

 

[eidairaman1]

The problem with ESD is the discharge can be so tiny we mere humans cannot see, hear or feel that a discharge even happened, yet that arcs can torch a Grand Canyon sized (microscopically speaking) scorched trench through millions of transistor gates.

Because they can be so tiny, I cannot be certain, but I believe I have killed several flash drives from ESD just from pulling them out of my pocket. Just another reason to make sure you put the cap back on them.

Oh the 1 ESD I had was definitely visible, hurt too. ESD is just static. Since then I touch the case before I touch usb drives or plugs. Some of us just have that higher capacitance to hold static.

I have killed 1 stick of ram via esd and it was non visible.

 

[Bill_Bright]

Oh the 1 ESD I had was definitely visible, hurt too. ESD is just static.

Oh yeah. In fact, for those reading unfamiliar, ESD stands for electro-static discharge.

To clarify, I did not mean to suggest no ESD events are visible, audible, nor can they be detected by the sense of touch. On the contrary, shuffling across the carpet and reaching for a door knob or the dog's wet nose can certainly result in a static discharge arc very visible, audible and easily felt - enough to send the dog running and an automatic recoil reaction that nearly rips your rotator cuff apart.

However, when it comes to extremely sensitive, high-density, integrated circuits like microprocessors and memory devices; devices with transistor gate gaps measured in single digit nanometers, those destructive discharges can be too tiny to see, hear or feel. Note an average human hair is about 100,000 nanometers wide.

As techs, we were unknowingly destroying these devices we were responsible to maintain. Not good. All we knew is the device didn't work. And the replacement often didn't work because we inadvertently zapped it during installation due to mishandling. We just didn't know we needed to discharge ourselves first.

This is why ESD was such a mystery at first. Early ICs were being returned as dead to TI, Motorola and other early chip makers with no apparent reason for their demise. It was only after visual examinations under powerful microscopes that those "Grand Canyon" size trenches (microscopically speaking) were seen. It took even longer to figure what torched them, and how to prevent them.

Sorry I was not more clear.

Anecdotal true story: I remember in the mid to late 70's when many of our air traffic control communications and ground control systems were [finally] moving away from analog and vacuum tube technologies to solid state and digital. We had to go back to school to learn about ESD and ESD prevention. And we could not work on any of the comms or NAVAIDS systems (with supervision) until certified again. That's about the time I got issued my first anti-static wrist strap. And we had to replace all our non-conductive floor and bench mats with special anti-static mats to ground ourselves to our benches, to the floor, to Earth ground, and to the equipment - ensuring we were all at the same ground potential, thus eliminating any chance of any static buildup that might result in a discharge.

 

[eidairaman1]

Oh yeah. In fact, for those reading unfamiliar, ESD stands for electro-static discharge.

To clarify, I did not mean to suggest no ESD events are visible, audible, nor can they be detected by the sense of touch. On the contrary, shuffling across the carpet and reaching for a door knob or the dog's wet nose can certainly result in a static discharge arc very visible, audible and easily felt - enough to send the dog running and an automatic recoil reaction that nearly rips your rotator cuff apart.

However, when it comes to extremely sensitive, high-density, integrated circuits like microprocessors and memory devices; devices with transistor gate gaps measured in single digit nanometers, those destructive discharges can be too tiny to see, hear or feel. Note an average human hair is about 100,000 nanometers wide.

As techs, we were unknowingly destroying these devices we were responsible to maintain. Not good. All we knew is the device didn't work. And the replacement often didn't work because we inadvertently zapped it during installation due to mishandling. We just didn't know we needed to discharge ourselves first.

This is why ESD was such a mystery at first. Early ICs were being returned as dead to TI, Motorola and other early chip makers with no apparent reason for their demise. It was only after visual examinations under powerful microscopes that those "Grand Canyon" size trenches (microscopically speaking) were seen. It took even longer to figure what torched them, and how to prevent them.

Sorry I was not more clear.

Anecdotal true story: I remember in the mid to late 70's when many of our air traffic control communications and ground control systems were [finally] moving away from analog and vacuum tube technologies to solid state and digital. We had to go back to school to learn about ESD and ESD prevention. And we could not work on any of the comms or NAVAIDS systems (with supervision) until certified again. That's about the time I got issued my first anti-static wrist strap. And we had to replace all our non-conductive floor and bench mats with special anti-static mats to ground ourselves to our benches, to the floor, to Earth ground, and to the equipment - ensuring we were all at the same ground potential, thus eliminating any chance of any static buildup that might result in a discharge.

You were fine on the previous post, just sharing my misadventures in electronics.

 

[plamy1969]

Someone said that the power button may be the problem and to to be sure I need to touch the pins with screwdriver on the motherboard to see if the PC will start or not.
So where do I need to do the operation from above? See my motherboard scheme attached here.

 

[Bill_Bright]

Just follow the two wires from the back of the case's front panel power button to where they connect to the motherboard. Your image is hard for me (and my old eyes) to see clearly but it looks like down at the bottom, there is a connector header labeled F-Panel. That would be where the two wire connect to the two pins you need to short together with a flat tip screwdriver. Note it only takes a quick (1 second) connect to signal the computer to turn on.

Your motherboard manual should show this too - and label each pin's function.

 

[Waldorf]

cant read it on the phone, but its the 2nd group of pins on the bottom, to the left of the sata ports.
your case should 6 wires, 2 for each (power/reset/hdd led).

see if you can trace the cable from to switch, or if you can see them, and they arent all identical in color, pull those 2, and thats the 2 pins u need to short.

 

[plamy1969]

Actually, I quit testing those pins on the motherboard, because today (after 4-5 days of unsuccessful attempts) my PC finally turned on. Again.
So the power button is definitely not the reason for my problem. Also, the power button ALWAYS works when I press it for few seconds until the PC turns off.
Most probably the reason may be a capacitor or a resistor that sometimes keeps the needed amount to let the system turn on, and more often doesn't. And probably that's why the Windows stops as well, but the power supply and all the fans keep working after shutdown/sleep. There is some electronic element which acts defectively and doesn't let the PC turn off and then turn on. Also, such an element may cause the PC to keep running inside after sleep or shutdown with still working fans and lights.

 

[Waldorf]

replace the psu with a different one, for troubleshooting, maybe a friend nd/relativ has a unit. do NOT reuse your cables (if its modular), just unplug all your power cords (inside) and hook up the other temporary.

 

[redeye]

is it plugged in… /o. buh dum bah… rimshot