Question Desktop PC powers on only with air conditioner turned on ?

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pandre

Jan 15, 2023
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My desktop pc fails to start (mainly in the morning) after being off for some hours. It only starts if I power on the air conditioner for some minutes. What can be the problem?

Additional info (January 17, 2023): I noticed that whenever powered up with the air conditioner on, the clock loses its settings. I will buy a new battery, but I am not sure if this will be of any help.
Another point, the problem started some 8 months ago and I have tried every suggestion I could find on the web. Two months ago someone suggested that the problem might be caused by high humidity. I put some dehumidifier inside the PC case and it helped (the PC was able to power on) but this did not last and soon the PC would not power up. I checked the level of water in the dehumidifier and exchanged it for a new one. Did not work! That was when it occurred to me that the air conditioning may be of help as it would remove the excessive dampness. And, it worked.
So, I believe that the problem might be caused by dampness. I live in Rio de Janeiro and since last July our weather has been very rainy.
 
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MJS WARLORD

MJS WARLORD

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The first thing i would do is get one of these ..... ATIN Plug Socket Tester Mains Fault Checker Detector AC 220-250V Malfunction : Amazon.co.uk: DIY & Tools

It will tell you if your wall sockets are safe

When you say air conditioner do you plug it into the same wall socket or is it a stand alone unit.

Please note plugs and wall sockets do strange things , a plug has no moving parts but if it is not a moulded one take the back off and see if the screws holding the wires have worked loose.
The same thing can happen to the wires on the back of a wall socket BUT DO NOT inspect these yourself because you might get a fatal shock.
 
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pandre

Jan 15, 2023
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It will tell you if your wall sockets are safe
Answer: Unfortunately, my wall socket is different than the one in the photo and the device is currently unavailable in Amazon. Anyway, I checked all sockets with a multimeter.

When you say air conditioner do you plug it into the same wall socket or is it a stand alone unit.
Answer: The air conditioner is a 220 V and my PC is plugged into a 110V . The air conditioner is in the wall on the other side of the room.

Please note plugs and wall sockets do strange things , a plug has no moving parts but if it is not a moulded one take the back off and see if the screws holding the wires have worked loose.
Answer: Thanks for the explanation. But this is not part of the problem. The PC cord plug is moulded. By the way, I exchanged the PC cord several times and also checked its continuity.

The same thing can happen to the wires on the back of a wall socket BUT DO NOT inspect these yourself because you might get a fatal shock.
Answer: Just for your information, I am an Electronic Engineer and know about the risks of working with electrical installation. But, thanks again for the warning.
 
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pandre

Jan 15, 2023
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COLGeek said:
Understood. I would have expected the opposite. Once the AC powered on, other devices like your PC not working would have been expected.

In your situation, it seems the opposite and that makes little sense. Are any other devices/appliances behaving the same as your PC?
Click to expand...
Answers: I did not understand what you meant by "...expected the opposite". Also in the next phrase you say "...that makes little sense." what makes little sense?
Perhaps I confused you when I wrote "...I tried to connect it...". In reality, I connected the PC to several other wall sockets, but it did not power on. It only powers on after some 5 minutes of the air conditioner being powered on. And after the PC is powered on, I powered off the air conditioner and it (the PC) continues to function normally.

Answer: No, no other devices/appliances behave the same as my PC. Please understand that after I power on the air conditioner for around 5 minutes I am able to turn the PC on and it keeps on even after I power off the air conditioner.

Thanks for your support
 
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pandre

Jan 15, 2023
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COLGeek said:
I would have an electrician check this out immediately. I suspect something is mis-wired that could prove to be dangerous.
Click to expand...
Thanks for the suggestion!
As a BSEE I feel I am qualified to do this checking. And I did it. Nothing wrong with the wiring. Please note that I connected the desktop to several other wall sockets and there was no change to its behavior. Besides, my notebook is connected to the same wall socket and it have no problem.

Another item that can influence the desktop power on process would be a bad CMOS battery (I never heard of it having such influence). I bought a brand new battery (CR2032) and replaced the one that was in the motherboard. Let's see what happen tomorrow morning.
 
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JayGau

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When you try to power it on and it doesn't work, what does it do? Nothing gets powered on like it's not plugged in or do the fans and LEDs start but it doesn't boot? What is the pecentage of humitidy in the room when it doesn't start and what is the percentage when it starts? You can find humidity monitors for less than 10$ online to measure that. If it does like it's not plugged in but other devices work in the same power outlet it could be something as simple as a humidity-related short-circuit somewhere that prevents the current to reach the motherboard front panel header when you press the power on button.
 
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COLGeek

COLGeek

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pandre said:
Can you please, explain the meaning of "You should not have to power on the AC to start your PC"?

I checked the power circuitry and did not find any power or grounding issues on the circuits.

Once again, thanks,
Click to expand...
Those are my words to explain your words "It only starts if I power on the air conditioner for some minutes". That statement, if I understand your intent, is very unusual and not something I would expect. If fact, as stated earlier, I would have assumed the opposite (more common scenario).
 
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pandre

Jan 15, 2023
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JayGau said:
When you try to power it on and it doesn't work, what does it do? Nothing gets powered on like it's not plugged in or do the fans and LEDs start but it doesn't boot? What is the pecentage of humitidy in the room when it doesn't start and what is the percentage when it starts? You can find humidity monitors for less than 10$ online to measure that. If it does like it's not plugged in but other devices work in the same power outlet it could be something as simple as a humidity-related short-circuit somewhere that prevents the current to reach the motherboard front panel header when you press the power on button.
Click to expand...
Nothing gets powered on. However the motherboard LED is on. The fans do not run. The PC does not boot.
I cannot tell you what is the percentage of humidity as I do not have an hygrometer. But the weather in Rio de Janeiro has been rainy for a long time and damp for some months.
My notebook is plugged in the same power outlet and is working with no problem whatsoever.
The humidity in Rio varied between 70% to 92% during the day with an average of 76%, I think that this is not too high.
I believe that you suggestion of of a humidity-related short circuit is the probable cause of the problem.

Thanks!
 
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Kona45primo

Kona45primo

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I like the humidity theory. Maybe get a bunch of those silica packets and see if those help lol.

I would do you best to maybe blow out the power supply and see if anything changes. Also confirm the switch behind the button isn't defective. You can usually get replacements for a few dollars. If nothing helps, perhaps try a new or borrowed power supply.
 
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pandre

Jan 15, 2023
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COLGeek said:
You should not have to power on the AC to start your PC. There is a power or grounding issue in the circuits or the strangest PSU error I've ever seen.

See what I mean?
Click to expand...
For sure I should not have to power on the air conditioner to start my PC! Unfortunately this is the method to power on my desktop!:confused_old:
I checked the circuitry and there is no issue in ground or power. Understand that my notebook is plugged in the same power outlet and works perfectly.
Because of the problem I bought a new PSU to no avail.
 
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pandre

Jan 15, 2023
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Kona45primo said:
I like the humidity theory. Maybe get a bunch of those silica packets and see if those help lol.

I would do you best to maybe blow out the power supply and see if anything changes. Also confirm the switch behind the button isn't defective. You can usually get replacements for a few dollars. If nothing helps, perhaps try a new or borrowed power supply.
Click to expand...

I did put two silica packets but they only worked for about one week. Then either the problem worsened or the packets lost their absorption capability.

I did not blow the PSU. I blown the the motherboard with a hot hair drier, but it did not work (I did not blow for a long time, afraid that it my damage the solder or some component).

The front of the case switch is OK.

I bought and installed a new and different brand of power supply to no avail.

Thanks.
 
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pandre

Jan 15, 2023
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JayGau said:
You could try that when it doesn't power on (before starting your AC I mean):

View: https://www.youtube.com/watch?v=G4FOBL1c3pA


If it works then it's the power button that doesn't apply the current properly to the front panel when it's too humid in your room. The fact that the MB LED is on shows that you have power but nothing gets turned on when you press the button.
Click to expand...

I did what the guy instructs. That was one of the first thing I tried!

Thanks,
 
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pandre

Jan 15, 2023
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COLGeek said:
Those are my words to explain your words "It only starts if I power on the air conditioner for some minutes". That statement, if I understand your intent, is very unusual and not something I would expect. If fact, as stated earlier, I would have assumed the opposite (more common scenario).
Click to expand...
My mistake. I did not realize that AC meant Air Conditioner. Sorry!
 
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