I'm building a computer for my friend.

We finished building it and tried to start it, but my natural enemy when it comes to building computers, the power button, doesn't work.

in the Manual on site 12 (1-4) we can see an info graphic how to connect the power switch, power led, reset switch, hdd led etc.

I actually connected them exactly like they say in the manual, but it won't work. nothing happens when I try to push the button. The mainboard certainly has got power because when I plug in the ethernet cable, the LED start to glow, which is an indication that the mainboard has power.

I also tried to "turn around" the power switch so the text on the cable faces the bottom instead of the top, and also i tried both position for the 2 one-pin power-led cables.

I made pictures of my setup but they're so low quality, It wouldn't help at all. sorry for that.

I know that there is probably not a straight forward solution to my problem, so what steps can I take to find out what causes the problem? thanks a lot!

EDIT/UPDATE: Hi guys, thanks for all your suggestions. The faulty part was the processor. It was the first time I installed an AMD processor instead of Intel. Intel processors have this kind of "cap" you put on top and close after installing the processor. AMD don't have that, you have to push them in by your own. looks like I didn't push enough the first time and the pins weren't correctly seated.

I'm gonna accept the answer that says that you need to check every component, because that's what saved me. If it doesn't work, start again from 0.

  • 1
    For the led cables, I believe that polarity matters (usually black wire is ground). For 2-wire normal-open momentary switches (power and reset switches), polarity does not matter. You can try using the reset switch on the power pins to see if you have a faulty power switch. – Yorik Feb 28 '18 at 15:13
  • 1
    You can also get a flathead screwdriver and use it as a bridge to make the 2 power pins touch. This should turn on the machine and let you know if the pins are bad. – Narzard Feb 28 '18 at 17:23
  • Did you connect the 4/8-pin EATX12V power to CPU? – Ale..chenski Mar 4 '18 at 6:43

The issue is probably not the power button - rather a faulty or incorrectly seated component. (Could be anything except the hard disk really, RAM is a common one).

Also, assuming the system has a CPU and/or PSU fan, if they are not spinning, the system does not have power or the motherboard has failed - it's unlikely but possible the network card LED is being powered off power coming down the Ethernet cable.

  • so the PSU or CPU fan should start spinning when I plug in the power? Don't they start spinning only if i start the computer? – SimonS Mar 1 '18 at 9:09
  • The PSU fan will only start spinning when they receives the signal from the motherboard - but this is, effectively just equivalent to shorting psu-on (pin 14) on the PSU. You typically don't need a CPU installed on motherboard for fans to spin. – davidgo Mar 1 '18 at 9:16
  • sorry i don't really get it. the psu fan will spin when ever he receives a signal from motherboard and power is plugged in? that means the psu fan spins always, even when a computer is powered of? I think I need to power-on the computer (which i cant) to get the fans spinning, or am I completely wrong? – SimonS Mar 1 '18 at 9:19
  • You are right - you need to press the power switch - or emulate that by briefly shorting the appropriate pins on the motherboard. The problem is unlikely to be the switch though. – davidgo Mar 1 '18 at 9:23

First, make sure you have the 4/8-pin EATX12V connected. Without this connection the board won't start.

Second, check if you have +5V_STBY voltage at 5 V,

enter image description here

This voltage should be "always on" as soon as the computer PSU is connected to AC outlet. If the standby voltage is not there, or low (less than 4.5V), either the mainboard has a fault, or your PSU has insufficient standby power rating (it should be no less than 2 A).

Check if the power switch makes a short between pins if you press the power button. You can try something conductive (like tweezers or screwdriver) to initiate the power-on by shorting corresponding pins on the "panel" header.

Before doing the above, disconnect all peripherals (disks, CDroms, etc, even video card and all USB), leave only CPU and memory. Even if you have no peripherals and can't see/do anything, the CPU fan should start spinning. And "RGB strip" should light on.

If still nothing happens, check if some ICs or secondary power supplies (on-board) are too warm to the touch. If yes, your board is likely damaged.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.