5 Replies Latest reply on Jun 17, 2015 6:49 PM by N.Scott.Pearson

    Front Panel Header questions


      I am in the process of purchasing a NUC5i5RYH to put into an enclosure that will house other electronics and peripherals.  Instead of removing the lid on and off everyday to turn off the NUC, I was planning to add a remote on/off switch to the enclosure that will connect to the Front Panel Header.


      I have multiple questions, so please bear with me.


      What is the voltage output across pins 2 and 4 of the header?  This is the power LED indicator.

      What is its supply current capability across 2 and 4?  I just need enough to turn the LED on.

      Since my remote switch has a built in LED is there a pull up resistor near that connector?  Or do I have to provide one?


      Most desktop PC's have three power switch conditions.  One, if you hit it once it will turn on the PC.  Two, if you hit it again it should reset/reboot the PC.  And three, if you push it in again and maintain for 5 seconds it will turn the PC off.  Since, I am using the Front Panel Header will this be the same case when connecting my remote switch across pins 6 and 8?


      I see that pins 5 and 7 are for a reset switch.  If the condition explained above are not the case then this means that I will require two switches?  One for the reset (pins 5 and 7) and another for the power switch (pins 6 and 8)?


      Any help will be greatly appreciated.

        • 1. Re: Front Panel Header questions



          The correct mode of operation for the (momentary contact) power button is as follows:


          • If the system is powered off, pressing the power button once (holding it for less than three seconds) will power on the system and initiate the BIOS POST and O/S boot process.
          • If the system is powered off, pressing and holding the power button for three seconds will cause the system to power up and the BIOS recovery menu to be produced (this is a BIOS feature).
          • Pressing the button again before the O/S takes control will immediately power off the system.
          • Pressing the button again once the O/S has taken over control will, depending upon the configuration of the O/S, either cause an orderly shutdown of the O/S followed by a system power off, or will cause the system to be put to sleep. In no case should this cause the system to perform a reboot (unless the never-shuts-off-always-reboots issue is occurring on your system).
          • Pressing and holding the power button for four seconds will cause an immediate power off of the system. This is a chipset feature and cannot be reconfigured via BIOS.


          There is no way to generate a system reset using the power button. This has never been a capability supported by Intel processors/chipsets. You need to have a separate (momentary contact) reset switch (yes, connected to pins 5 and 7) to cause a hard, non-interruptable system reset.


          The TPS for the board does not answer any of the questions to have concerning voltage and current across pins 1 and 3 and across pins 2 and 4. I have sent a message to one of the TMEs asking them to have an answer provided for these questions.



          • 2. Re: Front Panel Header questions



            I forgot that there is a separate switch for the reset on all PC cases and your details on the mode of operation for the power switch are spot on.  Thank you for clarifying it for me.  Hope to get the additional information regarding the voltage and current spec's of the Front Panel Header soon.


            Again thanks for the help.

            • 4. Re: Front Panel Header questions






              Initially, this is where I got the information.  The only thing this is lacking is the voltage and current values that I am looking for.  Thanks for the link.


              • 5. Re: Front Panel Header questions



                Here's the answer that I got from the engineering team: "Pins 2 and 4 are pulled up to 5V with 330ohm resistors". I am a software guy, not an EE, but I believe you can calculate the current from there...