Question What does it mean if I short the power switch pins but the PC still doesn't power on ?

[jjordvnn]

I just got off work and tried to turn my pc on (per usual) but today it wasn’t powering on when i pressed power button. Did some basic research and learned i can short the pins to give it a jump start which i did but it didn't work. I then shorted my PSU and my PC powered on . So after seeing that shorting my psu powers it on but shorting the power switch pins doesn’t, could that mean my motherboard needs to be replaced ?

I have an ASRock B550 motherboard.

 

[SkyNetRising]

Probably shorting the wrong pins.
What is full model name of the motherboard?
There are at least 18 asrock b550 models.

 

[CountMike]

I just got off work and tried to turn my pc on (per usual) but today it wasn’t powering on when i pressed power button. Did some basic research and learned i can short the pins to give it a jump start which i did but didnt work. I then shorted my psu and my pc powered on . So after seeing that shorting my psu powers it on but shorting the power switch pins doesn’t. Could that mean my motherboard needs to be replaced ? I have a b550 asrock mobo. Helpppp:///

Shorting pins for startup just checks for Start button operation as it's just a most simple, 2 contact, momentary switch, like for a door bell.
Shorting green and black leads on PSU 24 pin is not a full check of PSU so it can still be at fault.

 

[jjordvnn]

Probably shorting the wrong pins.
What is full model name of the motherboard?
There are at least 18 asrock b550 models.

I cant find the exact model but isnt it the power sw connector that in supposed to take off and short?

 

[SkyNetRising]

I cant find the exact model but isnt it the power sw connector that in supposed to take off and short?

Model name would be written on the board itself.
Also you can find model name with CPU-Z - motherboard section.

Different boards will have different front panel connectors.
To find correct pins, you have to read motherboard user manual first.
Therefore - find motherboard model name.

 

[jjordvnn]

Model name would be written on the board itself.
Also you can find model name with CPU-Z - motherboard section.

Different boards will have different front panel connectors.
To find correct pins, you have to read motherboard user manual first.
Therefore - find motherboard model name.

ASRock B550AM GAMING AM4 microATX DDR4 WIFI Motherboard​

 

[jjordvnn]

Shorting pins for startup just checks for Start button operation as it's just a most simple, 2 contact, momentary switch, like for a door bell.
Shorting green and black leads on PSU 24 pin is not a full check of PSU so it can still be at fault.

Understood but if the psu was at fault it wouldn’t had powered on and supplied power to the other components? How can i do a full check to rule it out?

 

[CountMike]

Understood but if the psu was at fault it wouldn’t had powered on and supplied power to the other components? How can i do a full check to rule it out?

No. PSU supplies power to MB with more than dozen places thru different channels, voltages and polarities and if one is out of specs or not working, MB will not fully energize and all components work. Testing could be done by dedicated instrument, in a pinch with voltmeter or by changing for some known good and compatible PSU.

 

[Ralston18]

@jjordvnn

FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

 

[Calab]

This is the front panel diagram that I see from the ASRock website. It looks like it's a common setup across thier MBs. Just jump the PWRBTN# pin to GND for a moment and the PC should come on - if the MB and PSU are working.

 

[CountMike]

This is the front panel diagram that I see from the ASRock website. It looks like it's a common setup across thier MBs. Just jump the PWRBTN# pin to GND for a moment and the PC should come on - if the MB and PSU are working.

That layout is pretty well standard on all MBs for quite a while.

 

[SkyNetRising]

That layout is pretty well standard on all MBs for quite a while.

That's not a standard.
There are quite a lot of different front panel connector variations.

 

[CountMike]

That's not a standard.
There are quite a lot of different front panel connector variations.

Notice "pretty well" ?? Because I'm using same case I still use same quick change adapter from a Gigabyte MB from 7 MBs ago.

 

[bill001g]

A couple things to check. You will need a multimeter to do most this.

First make sure the switch going to front panel is not shorted. The pins it connects to on the motherboard are only designed to be temporary connected. When you release the button the are not connected. Some motherboard do not actually boot until you release the button. So it wants a closed connection that is then opened again if it stays closed it does not boot.

Next is gets more involved. Get a diagram of the 24 pin connector. If you can get your multimeter leads in the case you should be able to measure voltages by placing the probes into the top of the connector. I disassembled my power supplly and test inside which of course is more risky but only way I had access to the wires.

What you want to first check is pin 9 and make sure this is 5 volts. This is what is called +5vsb. It should always have power as soon as the main power supply switch is turned on. Nothing works without this.

To see if the motherboard is doing what it is suppose to you want to check pin 16. What you should see is when you temporarily connect the 2 pins that go to the front panel the motherboard will connect pin 16 to ground.

This really is the only failure that would be the motherboard itself if it does not correctly do this function. Everything else is likely a power supply issue.

The power supply I had fail a couple days ago happly put out the 5vsb power and the motherboard correctly grounded the green wire (pin 16) but nothing happned. Nothing appeared damaged inside the power supply and quick checks for shorts of capacitors or resistors showed nothing so it must be some fancy chip doing this and without a digram not going to even try to find it.