[SOLVED] Pc Not Turning on After a Power cut.

Feb 12, 2020
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Hey guys and gals, pretty new to this site but have seen countless topics answered so I thought I would give it a shot myself.

So here goes (sorry for the long thread) :

3 days ago I was using my pc and it was running perfectly fine until our street had a power cut for about 2 minutes. It comes back and all of a sudden my Pc does not turn on at all when I press my power button.

I have tried all the suggestions listed:

  • Turned it off by the switch on the back and even the main plug sockets.
  • Unplugged it from the mains and all the cables on front and back and left it overnight.
  • Tried plugging it into another room entirely; that I know for sure there is nothing wrong with the sockets.
  • Opened the Case up and unplugged my PSU, Graphics card, RAM Sticks from the Motherboard and put them back in. (I swapped the RAM Sticks over as well)
  • Replaced my CMOS Battery with a brand new one.
  • Bought a brand new Modular Psu 750W gold rated and replaced old one.
  • Tried to power it on via the power switch pins using a Flathead screwdriver.
  • Held the power button for 10 seconds to see if that did anything but no.
Everything I have tried has not worked, however; I do see a green light on the Motherboard that says "Sb_pwr" so I would assume that means there is power going to the motherboard.

So it can't be an issue with the Motherboard and definitely not a brand new Psu. Whenever I press on the power button, nothing happens; no movement, noise, other lights or anything.

Alright now that I have put all that down here are my Specs:

  • I7 4790k Processor 3.5ghz
  • 16 gb RAM (3 sticks)
  • EVGA Geforce GTX 1070
  • Asus H97 Pro Motherboard
  • EVGA 750GQ PSU 750W
  • Arctic Freezer 13 (Huge fan in the middle)
  • 500gb SSD (Main OS) (Santander is the make)
  • 2TB HDD (Seagate I believe is the make)
Not sure if you guys want the keyboard and monitors, etc but I will include them just in case.

Razer Blackwidow Chroma is the KB
Razer Death adder Chroma is the Mouse
Main monitor: 24" Asus 144hz
Secondary Monitor: Acer KG241Q

And there we have it. I hope you guys can help me out with this because I'm going crazy trying to figure it all out.

I appreciate you taking the time to read it I know it's a long thread but trying to give as much info as possible for you.
 
Even if a motherboard has a green light or power goes thru it, it could have failed if the PSU did not have appropriate protection.
When the power returns, it can cause a surge, or spike that could be transferred to the PC components.
A motherboard could shut itself to protect components.
Draining the capacitors could bring the motherboard back if it has not failed.
You could drain capacitors by unplugging the PSU from motherboard and pressing the power button several times.

Test your system without the GPU, one stick of RAM, not disks, and no USB peripherals to see if it posts.
What was the PSU brand you had when the power was interrupted?
 
Even if a motherboard has a green light or power goes thru it, it could have failed if the PSU did not have appropriate protection.
When the power returns, it can cause a surge, or spike that could be transferred to the PC components.
A motherboard could shut itself to protect components.
Draining the capacitors could bring the motherboard back if it has not failed.
You could drain capacitors by unplugging the PSU from motherboard and pressing the power button several times.

Test your system without the GPU, one stick of RAM, not disks, and no USB peripherals to see if it posts.
What was the PSU brand you had when the power was interrupted?
 

cin19

Titan
Moderator
The Sb_pwr only shows you the PC get power, and from you said what you try, I think either the MB or cpu may have problem.

You may try to remove the GPU, all the RAM, and disconnect the boot device, use onboard iGPU, clear the CMOS by the jumper.

After that, boot the pc without RAM and boot device, keep in mind you will not boot pc into the window, but you will get no RAM and no boot device error, if the MB/CPU are fine. If you will get the same, that means either the MB or CPU has problem.
 
Hey there,

No apologies for the long thread. It's quite detailed, and actually very helpful! :)

So, the light on the mobo (afaik) indicates only that there is power going to the mobo. It does not indicate the mobo is functioning correctly.

With a power outage, it's very possible the mobo/CPU/ram has been damaged. That is hard to tell, unless you have another PC that you can swap out parts with and test. That is the only real route to diagnosing the problem.

@jojesa made a good suggestion. Try that, but if it doesn't work, the best, quickest way to resolve this, would be to bring to a local store, and get them to test your individual parts to find out which one isn't working. You could do this with a second PC (if it was a similar build). Maybe a friend could help you out?
 
Feb 12, 2020
9
1
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Even if a motherboard has a green light or power goes thru it, it could have failed if the PSU did not have appropriate protection.
When the power returns, it can cause a surge, or spike that could be transferred to the PC components.
A motherboard could shut itself to protect components.
Draining the capacitors could bring the motherboard back if it has not failed.
You could drain capacitors by unplugging the PSU from motherboard and pressing the power button several times.

Test your system without the GPU, one stick of RAM, not disks, and no USB peripherals to see if it posts.
What was the PSU brand you had when the power was interrupted?
The brand before was a Corsair CX750W to be specific. When you say no gpu. Should I just unplug it from psu or take the card out the Slot? Also when you say press the power button a few times do I hold it for X amount of seconds each time or just press it?
 
Feb 12, 2020
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Which Corsair Model?
Corsair makes excellent high quality 750W PSUs and also some 750W cheap units.

keith12 made a good point on his post^.
Unless you have spare parts to test each components,your best bet is a repair shop.
I think the model is CX not too sure since I have had this build for a good 7 years or so (the 1070 is probably the most recent upgrade).

I will try draining the capacitors like you said and I might have some spare RAM sticks lying around somewhere.

If worse comes to worse I'll just have to take it to a repair shop, not sure what they charge nowadays since I have never had an issue as severe as this before.
 
I think the model is CX not too sure since I have had this build for a good 7 years or so (the 1070 is probably the most recent upgrade).

I will try draining the capacitors like you said and I might have some spare RAM sticks lying around somewhere.

If worse comes to worse I'll just have to take it to a repair shop, not sure what they charge nowadays since I have never had an issue as severe as this before.
For a diagnosis, it should be no more than 20-30£$€.

The EVGA GQ line is a solid PSU, and is a much better PSU than the CX. You chose well.
 
Reactions: Alyx_Mist
Feb 12, 2020
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Alright I just unplugged my gpu, and tested with 1 ram stick. I got nothing. HOWEVER; I tested another 1 of my other sticks in another port and got a split second of power where the gpu started spinning

Edit: wait how did my gpu turn on when I unplugged it from the PSU?
 
Alright I just unplugged my gpu, and tested with 1 ram stick. I got nothing. HOWEVER; I tested another 1 of my other sticks in another port and got a split second of power where the gpu started spinning

Edit: wait how did my gpu turn on when I unplugged it from the PSU?
The GPU gets power from the motherboard PCI-e slot.
You should removed the GPU, while unplugged to avoid further damage.
Be careful touching components, like motherboard and GPU, since they could have some stored power on capacitors.
 
Reactions: Alyx_Mist
Feb 12, 2020
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The GPU gets power from the motherboard PCI-e slot.
You should removed the GPU, while unplugged to avoid further damage.
Oh OK so let me remove the gpu entirely and see how it goes

Edit: Even if I take the entire card out there is still about half a second of power.
 
Last edited:

cin19

Titan
Moderator
Both hard drives? do you mean the 500GB SSD + 2TB HDD? If yes, connect the boot device (SSD), then try to boot the PC. If you can boot the PC, that means the HDD has problem. If you can't boot the PC when you connect the SSD, that means the OS/SSD has problem, because when the power was cut off, the OS may corrupt, or the SSD did fail.
 
Reactions: Alyx_Mist
Feb 12, 2020
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Both hard drives? do you mean the 500GB SSD + 2TB HDD? If yes, connect the boot device (SSD), then try to boot the PC. If you can boot the PC, that means the HDD has problem. If you can't boot the PC when you connect the SSD, that means the OS/SSD has problem, because when the power was cut off, the OS may corrupt, or the SSD did fail.
I tried plugging the GPU back in, it runs when it's in the gpu slot but when I go to plug it into the PSU it doesn't want to power it.

Also which slot of the PSU do I put the GPU in? Because there seems to be some resistance when I try the cpu2 slot

EDIT: I figured out the issue and the graphics card is running fine. Turns out I had to use the provided cables from EVGA as the PSU would not take the old gpu cable.

Now to figure out which hard drive us faulty and the pc should finally be up and running.!
 
Last edited:

lynx1021

Reputable
Feb 17, 2016
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OMG! Never use modualar cables from a different brand power supply, it can fry your GPU or motherboard! The GPU power cables usually say PCIE on them. Use only the cables fom a modular supply that come with it!
 
Reactions: Alyx_Mist
Great ! it looks like it might have been a disk issue. 🤞
Also which slot of the PSU do I put the GPU in? Because there seems to be some resistance when I try the cpu2 slot
You should place the GPU on the top PCI-e slot.

EDIT: I figured out the issue and the graphics card is running fine. Turns out I had to use the provided cables from EVGA as the PSU would not take the old gpu cable.
Oh yeah, you should always use cables that came with the PSU. Don not interchange cables from different Manufacturers.

Now to figure out which hard drive us faulty and the pc should finally be up and running.!
If you installed Windows while both disk were plugged, if any of then fail then Windows won't boot.
To avoid that issue, when installing Windows, just connect the disk where Windows is been setup. You could add disks later on.
 
Reactions: Alyx_Mist
Feb 12, 2020
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-----UPDATE----- The pc is running fine now thanks to everyone here for the consistent help.

The hard drives seem to work as well it had the same issue as the graphics card, I had to use the EVGA supplied SATA Leads as it would not take the old ones.
 
-----UPDATE----- The pc is running fine now thanks to everyone here for the consistent help.

The hard drives seem to work as well it had the same issue as the graphics card, I had to use the EVGA supplied SATA Leads as it would not take the old ones.
Glad your system is back on.
So it looks like it was just the previous PSU that took the hit.
Everything else was working ...it was just the wrong cables connected. ;)
 
Reactions: Alyx_Mist

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