[SOLVED] Cousin's PC will not turn on, trying to diagnose the cause.

Cyber_Akuma

Distinguished
Oct 5, 2002
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Yeah, these are always fun since it could be just about any vital component and sometimes even non-vital ones that cause it.

From what I recall, his specs are:
OS: Windows 7
CPU: i7-4770K
PSU: Seasonic SS-760XP2 760W
Motherboard: Asus Z97-PRO(Wi-Fi ac)
GPU: GTX 770, don't recall the make.
I don't remember the rest of the specs, but I don't think they are relevant to this.

My cousin told me that his PC suddenly stopped working and would not turn on, he sent me this video:

https://photos.google.com/share/AF1...?key=cWZOaVJwTUswdDNrRWxyYkwzU21McE4yb0FENl9n

I went over to check, pressing the power button just made the PC attempt to power on for half a second, then shut off, and it would loop like this until you did a forced shutdown.

The motherboard has a POST code display, but it would just show 00 on it, which leads me to believe that it's not even trying or getting able to POST before it shuts down. I really hope this means that the issue is likely something else and not the motherboard, especially since IIRC this model of motherboard can function in an emergency BIOS re-flash mode with nothing but a PSU and USB drive connected to it, not even a CPU.

Normally I suspect the PSU in these cases since that has almost always been the case in my personal experience. I removed the GPU just to be safe and connected the HDMI port to the motherboard's internal video, there was no video signal detected. I tried making sure all the connections were not loose, use different cables or ports on the modular PSU for the necessary power connections, etc, nothing. Even stranger the motherboard/PSU seemed to be keeping power (there is an internal backlit power button on the motherboard for testing purposes that acts as the case power button, even with the PSU's physical switch set to off and the power cable unplugged from the wall this button was still lighting up, unplugging the ATX20 cable was the only thing that turned it off) even with the physical PSU switch off at times. Nothing was making a difference until I attempted to run it with the additional (I think it's called CPU power?) 8-port connector removed. I wasn't expecting it to turn on at all or just keep looping since that is a mandatory power connector, but instead it stayed on this time and the video even flickered. It still would not POST since from what I understand that is a mandatory connection in boards these days, but there was some different behavior at least.

According to the PSU's manual all of the ports in that connector are just simply 12V, so I got a multimeter and tried testing them, but was surprised to find that they were all delivering 12V. I tried to use the multimeter on the ATX20 connector to see if anything there was delivering the incorrect or no voltage but could not get the probes to come in contact while it was plugged in. I tried unplugging the ATX20 connection and jumping the power-on pins..... but he didn't have anything on hand that I could use to jump it, the only insulated wire he had was speaker wire that was far too thick to go in the connectors. So we ordered a PSU tester, it's set to arrive on Tomorrow.

And there is where I am right now. I am not sure what else to do if the PSU tester shows up as the PSU being fine, so I wanted to ask for advice, both on what could be the case and what else I can try if the PSU turns out to be fine. The next part I would suspect is the motherboard, but I am not aware of any real way to test that short of buying another motherboard and completely disassembling and reassembling the PC, plus if we can't get the same motherboard that likely means a Windows reinstall as well.

Any advice or tips about this?
 
Solution
There's 3 suspected failure, either 1 of them or all of them.
  1. PSU
  2. Motherboard
  3. CPU
But first, rule out everything. Rule out the CMOS battery replace it and reset the BIOS, leave just 1 ram and reseat it into another slot and putting it back again to the original slot, replace the video card or use the internal graphics, clean the processor's thermal paste including your whole CPU and heat sink, make sure to also clean the ram with an eraser (the gold in it), check the power cables of CPU and monitor including the ones for the signal bc most of the time the cable is the culprit like my PC which shutsdown turns out I have a bad power cable. The last one will be testing the PSU, try to paper clip test it. If the fan dont...

dajuukes

Prominent
Jun 28, 2019
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I found some similar issues on other threads:
Here and here .

I would suggest taking out the CPU and cleaning the motherboard with isopropyl alcohol, and attempt a fresh install. From what you described, the issue sounds related to the CPU.

Since you mentioned the board being able to boot without a CPU, try taking the CPU out and doing that. If that doesn't work, it's likely the motherboard.
 

USAFRet

Titan
Moderator
I found some similar issues on other threads:
Here and here .

I would suggest taking out the CPU and cleaning the motherboard with isopropyl alcohol, and attempt a fresh install. From what you described, the issue sounds related to the CPU.

Since you mentioned the board being able to boot without a CPU, try taking the CPU out and doing that. If that doesn't work, it's likely the motherboard.
"boot without a CPU" ?
It cannot do that.

" cleaning the motherboard with isopropyl alcohol"
Why? What would that solve?
 

dajuukes

Prominent
Jun 28, 2019
22
4
525
"boot without a CPU" ?
It cannot do that.

" cleaning the motherboard with isopropyl alcohol"
Why? What would that solve?
I'm just as confused as you are on the "boot without a CPU" thing. Whatever the OP meant is probably different than what I interpreted.

Regarding the alcohol, it's just my routine to clean around a socket. I doubt it really has any effect, I just like to cover bases.
 

madartzgraphics

Reputable
Jun 29, 2019
282
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4,790
There's 3 suspected failure, either 1 of them or all of them.
  1. PSU
  2. Motherboard
  3. CPU
But first, rule out everything. Rule out the CMOS battery replace it and reset the BIOS, leave just 1 ram and reseat it into another slot and putting it back again to the original slot, replace the video card or use the internal graphics, clean the processor's thermal paste including your whole CPU and heat sink, make sure to also clean the ram with an eraser (the gold in it), check the power cables of CPU and monitor including the ones for the signal bc most of the time the cable is the culprit like my PC which shutsdown turns out I have a bad power cable. The last one will be testing the PSU, try to paper clip test it. If the fan dont spin it's dead, if it spins, leave it for some minutes. I have a PSU that don't give the right power and blew up while paper clip testing it. Make sure to separate it first from everything before doing that. This is also the right time to check your front panel switch, try to remove the connector of it and short the 2 pin to make sure that the button isn't faulty. Check the graphics card thermal paste too. I did exactly the same process as I have the same issue 2 days ago. It's now alive by replacing the PSU.

If it's the PSU, check everything else because there's a big chance it fried your hardwares especially the motherboard and CPU. Like mine, the local power is the culprit. Usually, our power flicker, surges, outages and blacks out due to power outage, crisis and thunderstorms. It fried my AVR and PSU.
 
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Solution