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Topic: Motherboard pins and chassis plugs for LEDs and switches (Read 7143 times) previous topic - next topic
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Motherboard pins and chassis plugs for LEDs and switches

Hey guys, my PC parts arrived a few days ago and I started to build my PC. However, there is one small thing I don't really understand...

The Antec case has these plugs (number of holes in paranthesis):

RESET SW (2)
POWER SW (2)
POWER LED (3, however, I don't recall if all 3 have wires or only 2)
HDD LED (2)

Then the mainboard has these pins (again, number of pins in paranthesis):

PWR_LED (3): This header can be used to connect a system power LED on the chassis to indicate system power status. The LED is on when the system is operating. The LED keeps blinking when the system is in S1 sleep state. The LED is off when the system is in S3/S4 sleep state or powered off (S5). The pins are indicated with MPD+,  MPD- and MPD-. These pins are also slightly separated from the rest.

MSG (2): Connects to the power status indicator on the chassis front panel. The LED is on when the system is operating. The LED keeps blinking when the system is in S1 sleep state. The LED is off when the system is in S3/S4 sleep state or powered off (S5).

PW (2): Connects to the power switch on the chassis front panel. You may configure the way to turn off your system using the power switch (refer to Chapter 2, "BIOS Setup," "Power Management Setup," for more information).

SPEAK (4): Connects to the speaker on the chassis front panel. The system reports system startup status by issuing a beep code. One single short beep will be heard if no problem is detected at system startup. If a problem is detected, the BIOS may issue beeps in different patterns to indicate the problem. Refer to Chapter 5, "Troubleshooting," for information about beep codes.

HD (2): Connects to the hard drive activity LED on the chassis front panel. The LED is on when the hard drive is reading or writing data.

RES (2): Connects to the reset switch on the chassis front panel. Press the reset switch to restart the computer if the computer freezes and fails to perform a normal restart.

CI (2): This motherboard provides a chassis detection feature that detects if the chassis cover has been removed. This function requires a chassis with chassis intrusion detection design.

NC (1): No connection.

I connected the HDD LED of the case to the HD pins and the LED really lights up when the drive is working.
I connected the RESET SW of the case to the RES pins and the reset function works.
I connected the POWER SW of the case to the PW pins and the system starts up when I press the power button.
I connected the POWER LED of the case to the PWR_LED pins. At first the LED did not light up but after turning the plug around 180° it worked.

Now the CI pins are unused because the case does not provide intrusion detection, NC is left since it has no function anyways, SPEAK is unused because the case doesn't have a speaker and MSG is unused since I have no idea what it does.  MSG seems to be the same thing as PWR_LED, or am I wrong?

You are now probably asking "Why bother if everything works?". Well, the problem is that the system does not power off after telling Windows to shut down. I installed all drivers and the Device Manager does not show any problems. Putting the system in S3 mode seems to work and waking up works as well (although it takes half a minute for the display to resume from suspend state and show an image). However, when telling Windows to shut down, the usual shut down screen appears and after a while the screen goes blank and the display goes in stand-by mode, but all fans are still rotating (PSU, CPU, case and video card) and the power LED is still on.

Any idea what is wrong? Am I supposed to connect the power LED to the MSG pins? Windows seems to have powered off correctly because after restarting the system, it boots normally whereas cutting the power while the system is running results in a warning message the next time Windows loads (also asking if I am willing to send an error report to MS).

Motherboard pins and chassis plugs for LEDs and switches

Reply #1 –
My guess is that your lengthy post has nothing to do with your problems and is more likely to do with ACPI.

Either Windows has never been doing it right on your machine before, i.e. you've always been devolving to S4-S5 and this motherboard doesn't handle that power state.  Reinstalling the proper and latest chipset drivers is the best approach here.

Or this could be a Bios setting that's not set properly.

Sorry I couldn't be more helpful.

Motherboard pins and chassis plugs for LEDs and switches

Reply #2 –
Well, I have to check if for some reason, "Herunterfahren" does something I don't want it to do. All I can say is that restarting and sleep work (the latter enters S3). "Herunterfahren" should set the system to soft off state which is S5. I can set the BIOS to handle stand-by as S1 or S3, but S3 consumes less power and I chose that (which works). I didn't try hibernating Windows (S4).

Motherboard pins and chassis plugs for LEDs and switches

Reply #3 –
Problem solved! The reason why the PC remained on was the Gigabyte SATA RAID controller which had the wrong drivers installed. During the installation I selected IDE operation mode, but the BIOS setting was AHCI. After replacing the driver everything works fine.

As for the other question, I found out that some cases have a two holes plug while others have three (like mine). Both PWR_LED and MSG do the same thing.