Have a strange issue with my computer. Started recently, when shut down, power switch will not turn on computer. If I pull the powercord for 20 secs or so, it will power on fine. Tried a new power cord, same symptoms.... Is this a failing PSU or motherboard issue?
It could be either. It could also be the case switch.
You can try these tests if you are comfortable working inside the case and with electricity. Please use proper static precautions!
On the motherboard there are the case headers. This is where the wires from your case connect to the motherboard.
One of those connections is the Power Switch. 2 wires. It will be marked PWR or SW. Remove this header, then (power supply plugged in and switched on) touch the 2 pins with a flat screwdriver blade to electrically connect them just briefly (you do not need to hold the connection long).
If the computer starts right up without problems it is your case switch. Replace it.
The second test:
- Turn off the computer, switch off the power supply, remove the power cord.
- Disconnect all the power connections to the motherboard and components, including the 20/24 pin main motherboard connector.
- Find the Green wire to the main motherboard connector and note the pin it goes into (usually #14 on a 20-pin, #16 on a 24 pin)
- Find any black wire, closest to the purple wire and note the pin it goes into.
- Plug in the power supply, switch it on.
- Using a small piece of wire bent into a horseshoe shape, connect the two pins together (connecting purple to black). This connection is constant. The supply will turn off if you disconnect your horseshoe wire.
If the power supply comes on without issue the problem is on the motherboard.
If the problem remains, it is in the power supply.
Please do not attempt these tests if you are not mechanically inclined. Take it to a computer shop and they can perform these tests for you for relatively little money.
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