I share your confusion – the descriptions in the Product Guide and Tech Spec documents differ, and are singularly unhelpful.
There’s information on the PME signal (it’s a PCI bus signal, as I suspect you are aware) here http://en.wikipedia.org/wiki/Power_Management_Event. I asked Intel phone support about it but they had no information. They were adamant that it was not related to my problem, which is detailed in the thread DZ68BC Spontaneously Reboots during Windows Installation
On my board the LED is off after a cold boot; when it comes on subsequently it is very "sticky"; I have to cycle power to turn it off. Incidentally there is a duplicate of this LED identified in the silkscreen near the buzzer, but it is not fitted to my board.
Hope this helps, My best guess is that if your board is otherwise working normally it's nothing to worry about.
Thanks, yes I saw your post about the reboots and have read-up on the PME bus signal. Just can't figure out what the LED means. You'd think the "Technical Product Specification" would have, well, "Technical" information but all it does is give the name of the LED and nothing about what it's on/off states indicate.
I see the same thing you describe here regarding the light staying on through reboots/etc. The only thing that extinguishes it is to completely remove power for a while, but after booting it comes on again. But Windows 7 x64 loaded up just fine (using RAID mode, single Intel 510 120gb SSD for system, 2x WD Caviar in RAID1 for data).
I did try changing some Wakeup settings in the BIOS, but that had no effect on the PME#_LED. Even disabling all the wakeup settings didn't get rid of the light. So I put them all back to defaults. I have also tried different combinations of Wakeup settings in the Intel 82579V adapter's "Power Management" tab, but nothing there seemed to have an effect either so I put them back to defaults as well.
The only "problem" I had was when I tried out the "wake on LAN" functionality. It actually worked just fine -- I sent a wakeup packet, and the system came to life just as it should. But then when I subsequently shut down the system, it would not start up again. When I pushed the power switch, lights/fans cam on for about 1 second then immediately powered down again. Holding the power switch until the motherboard "beep" did the same thing; it just immediately shut down again. I removed power for a couple minutes, plugged it back in, and and the system started up normally.
So I wonder if the red PME#_LED indicates some kind of problem or error with the wakeup signal or PME monitoring. Other than the problem described above -- which really doesn't matter to me, because I don't need any wakeup functions -- the board is stable and working fine. But it would still be nice to know what the heck the PME#_LED indicates when ON vs OFF.
Mine came on red once.
No issues with the functions and not using wake on lan.
Powered down computer, unplugged, waited for Caps to drain.. plugged back in and been fine ever since.
I do not use WOL, so it has me scratching my head.
I hit the same roadblock as y'all. Docs say what it is , but not what causes it.
Will be curious to find out.
I have discovered that 100% of the time that I put my DZ68BC in Win7 Sleep mode, the PME LED will light on upon waking up. Like every one else’s observation, I have to pull the plug to get it to turn off.
This is very disappointing as I have a case with a window in it and I don't want to be de-sensitized by always having a red light on. I have already had my water cooled heat sink fail and noticed this event right away because of the red CPU overheat LED came on. The overheat LED happens to be located right next to the PME LED. There is a good chance that had I been de-sensitized to the red light in that location that I would have missed the overheat signal and would have let the CPU cook.
Sleep mode is a great feature that I never use because of this “Feature”. It sure would be nice if this was fixed in some BIOS update (Hint, Hint).
I read your post with great interest -- because I not been able to figure out what causes the PME#_LED light to illuminate. I periodically notice it is on, but no idea what triggered it. Seeing your post, I thought you had found the answer with sleep mode.
But alas for my machine, it does not seem directly related to "sleep". My light was ON, so I shutdown and disconnected power until it went OFF. Powered on and booted to Win7, light still OFF. Put to sleep, light still OFF. Woke up (pressed key on keyboard), light still OFF.
Tried again, put to sleep and then woke up using power button. The PME#_LED is still OFF.
So for me, it isn't directly related to Win7 sleep. I periodically notice it is ON, but can't pin down what causes it to come on. I don't have a case window, so am able to more easily ignore it than you -- but it still bugs me. :-).
It sure would be nice if a friendly Intel engineer would stop by and let us all know what the ON/OFF states of this indicator actually mean!
This is strange. I observed what I wrote about a week ago. It took me a week to write it up in this blog because Intel's automat had difficulty signing me up in this community (their automated system where they send you a password was down).
In any case I experimented with Win Sleep and know what I documented above was accurate. However, I could not repeat it this morning. I have placed my mother board in Win7 Sleep a dozen times and woke it up by using the mouse, hitting a key, and pressing the power button. The PME LED has not come on at all.
I have not updated the BIOS to a new version, so we can rule that out. I have, however, gone into the BIOS and make some set up changes. Is it possible that you have done the same? The only other thing that I can think of that has changed (other than adding now applications) is that I got a Microsoft update. Is your system up to date with all the Microsoft patches? Has your LED turned on recently?
I realize that the light on doesn't impact my computer at all. I just don't like warning lights on when there is nothing wrong. Just like in my car, I depend on the instrumentation to tell me when something is wrong. Having a warning all the time trains me to ignore them. That’s when I start missing real warnings.
Yes, I have made a bunch of updates that could have affected this. Unfortunately, I have come to ignore the light over the last couple weeks (no case window, so I have to go looking for it). That means I can't really say when I last saw it ON, or when it stopped being ON, in relation to those updates.
Since last noticing it ON a few days ago:
- There have been a bunch of windows updates. No driver-level updates though.
- I used "Intel Extreme Tuning Utility" to raise turbo multipliers (thus changing them in BIOS). No power management or voltage changes though.
- I swapped fans on the FRONT and AUX headers, and changed fan duty cycles. (Another story... I did this because, at least in bios 0027, the AUX duty cycle settings have no effect on the AUX fan. The AUX fan always follows the duty cycle set for the REAR fan. Changes to the AUX fan duty cycle are allowed and accepted, but completely ignored. Changes to the REAR duty cycle affect both the REAR and AUX fans.)
- Just yesterday, a couple hours BEFORE our discussion and checking the light, I removed "Intel Pro Network 16.8.0 1/2/12" and installed "Intel Pro Network 16.8.1 2/14/12". Normally I would put strong suspicion here, given all the PME functionality in the network drivers. However, I checked all the individual network driver file versions before and after the update, and all were identical (in fact, I can't find anything different between these two releases). Have you installed this? If not, we can rule it out.
Some motherboard engineer apparently thought it was important enough to include a PME#_LED light, and even chose an "alert color" (red) for it. That leads me to believe that the illuminated state *probably* indicates some kind of error condition related to PME functionality. It isn't causing me any grief -- but I would still like to know what condition that engineer thought was important enough to warrant a bright red light.
This is kind of weirding me out. Yes I know “weirding” isn’t a proper word but it describes my situation perfectly. This morning I was able to put my computer to sleep many, many times without the PME Led illumining. I have come home from work, read your updates, and repeated EXACTLY what I have done this morning and I’m back to where I was a week ago. 100% of the time I put my computer to sleep, I get the PME LED to light bright red the instant I wake up my computer. I’m talking about the same millisecond I touch a key.
Let me be clear there… I have not entered the BIOS set up screen. I have not added any applications. I have not had any Microsoft updates. As far as I can tell, I have done the EXACT same thing separated by 18 hours of off time and have different results.
Please keep up this thread with any new observations; I’m sure there is something going on that we can figure out. I’m just at a loss at the moment.
I did some more testing and have discovered a couple of interesting things.
First... My PME#_LED has been recently OFF, and nothing I did in the way of sleep / wake (via keyboard, mouse, switch) would turn it ON. I did some more sleep/wake and shutdown/restart cycles tonight, and it was still OFF.
So I decided to try a wakeup packet. Put the machine to sleep, light still OFF. Sent the wakeup packet and... Nothing. Machine still asleep (and PME#_LED still OFF).
Thought perhaps I had disabled wake-on-lan (didn't remember doing so). Checked network adapter properties and wake-on-lan was enabled. So I rebooted, F2'd into BIOS to check there. It was enabled there too, so I hit ESC and chose "exit without saving changes". BANG - The PME#_LED came on.
Once the machine was up & running, with light ON, I put it to sleep again. Light still ON. Sent it a wakeup packet -- and it woke up!
I repeated the entire sequence, with exactly same results. Specifically:
1. Shutdown and removed power until LED extinguished. Reconnected power.
2. Started system and booted to windows normally. LED still OFF.
3. Put to sleep. Sent wakeup packet. Nothing, did not wake up.
4. Woke up via keyboard, shutdown/restart and F2 into BIOS. Light still OFF.
5. Just "looked" at power settings in BIOS, made no changes, hit ESC and exited without saving. LED came ON.
6. Let system start and boot windows normally. Light still ON.
7. Put to sleep. Light still ON. Sent wakeup packet -- system came to life. Light still ON.
So I'm not sure what to make of all that... It could be that the PME#_LED is supposed to indicate readiness for a wakeup event. At least for me, when it is OFF a wakeup packet is ignored -- and when it is ON, a wakeup packet works. But it makes no sense to me that going into the BIOS, and making no changes (just exiting without saving) would change the state.
Can you give that sequence a try on your machine, and see if you have similar results?
So I tried a few more things, starting where I left off in the previous posting...
(PME#_LED was still ON from last step)
8. Shutdown and disconnected power until LED extinguished.
9. Booted normally to windows. LED still OFF.
10. Opened NIC properties, disabled wake-on-lan. Shutdown. LED still OFF.
11. Power up, F2 into BIOS, disable wake-on-lan, "F10-Save and Exit". PME#_LED came ON.
12. Allowed windows to start. LED still ON.
13. Shutdown, reset LED by disconnecting power. LED now OFF.
14. Powered on -- LED immediately came ON -- allowed to boot into windows. LED still ON.
15. Opened NIC properties, enabled wake-on-lan.
16. Restart, F2 to BIOS, enable Wake-on-lan. "F10-Save and Exit". LED still ON.
17. Boot normally into windows. LED still ON.
18. Shutdown, disconnect power until LED extinguished.
19. Startup and boot to windows. LED still OFF.
20. Put to sleep. LED still OFF.
21. Woke up with keyboard. LED still OFF.
Doesn't make a lot of sense. The things that seem consistent through these tests:
A) With WOL enabled in BIOS and NIC, wakeup packet is ignored if PME#_LED is OFF.
B) If I go into the BIOS, look at power management (no changes), and Exit without saving -- the PME#_LED comes ON.
C) With WOL enabled in BIOS and NIC, wakeup packet is honored when PME#_LED is ON. (This assumes I went into BIOS, looked at power, and exited without saving -- thus turning the led ON as in step B).
D) Once the LED is ON, it stays ON until I remove power and wait for capacitors to drain.
E) If WOL is disabled in BIOS, the LED comes on as soon as system is powered up (and then stays ON until reset by disconnecting power).
I am starting to suspect that the LED is supposed to mean that PME/Wakeup functionality is either enabled or disabled -- but that there is some other error that is causing it to work inconsistently.