PC won’t turn on after power outage

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dmoak

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Jun 11, 2021
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We had a brief power outage this morning. Now my desktop PC, which is plugged in through a surge protector, will not turn on. I have confirmed that the power supply works by putting a jumper between the green and black cables. The power supply turns on, as does my cooling fan. I have also tried unplugging the power supply and holding the power button down for 30 seconds.

I am wondering if possibly my motherboard is fried. Are there any more troubleshooting steps I can try before I replace the motherboard?

The motherboard is a gigabyte B450M DS3H with an AMD Ryzen 5 3400G CPU.
 

Tanis

Shane
Joined
May 29, 2006
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4,336
Hi and welcome to TSG.

Jumping pins on a power supply is not really a good test. A failed PSU could easily show working like that but not be able to operate under load when connected to anything. The only truly reliable way to confirm if the PSU is dead or not is to swap in a good, known working PSU.

The most likely thing to fail on a sudden power cut is the PSU, however it could potentially surge the motherboard and other components when it goes. A surge protector will not stop this.

What is the exact make, model and wattage of the PSU and roughly how old is it?
 

dmoak

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Jun 11, 2021
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The power supply is an Antec EA-430 (430W). It’s a Gigabyte MB with an AMD Ryzen 5 3400G CPU.
 

crjdriver

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Jan 2, 2001
Messages
44,499
That is one of those earthwatts pw supplies and those are not the greatest quality; only a 3yr warranty. I would start by seeing if the board will POST in a very basic config. Do the following;
1 System OFF and pw cord removed, open the case. Pull the pw connectors from ALL drives
2 If you have any add-in cards ie real sound card, raid controller, etc, remove those. Leave the video card installed. Since you have a "G" series, you may not have a real video card
3 Disconnect any usb device ie printer, hub, scanner, etc. Leave the keyboard connected
4 Clear cmos using the clear pins and not by pulling the battery out. Clear for at least 10 seconds
5 Replace the pw cord and attempt to pw ON. See if the board will POST. If it does, then shutdown and start connecting devices one at a time until you find the failed part. If the board will not POST in the above config, then you will need to swap parts with known good units; ie pw supply, motherboard, ram, etc
 
Last edited:

crjdriver

Moderator
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44,499
BTW jumping the pins on a pw supply is worthless. It does nothing to test the unit under a load.
 

dmoak

Thread Starter
Joined
Jun 11, 2021
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Other than the purple wire, I get no voltage on any of the other wires (red, yellow, orange). I’m thinking the power supply is dead.
 
Joined
Jun 12, 2021
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8
Other than the purple wire, I get no voltage on any of the other wires (red, yellow, orange). I’m thinking the power supply is dead.
The purple wire (+5VSB) should be +5 volts. If the voltage is lower, the motherboard power control circuitry won't work right.
 

plodr

Liz
Joined
Jun 27, 2014
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25,193
my desktop PC, which is plugged in through a surge protector
Remove the surge protector. That might have suffered damage.
For a short time, you can plug the PC directly into a wall outlet to test things.
 
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