I've seen several discussions about Precision M6500 blackouts. The diagnosis seemed to be related to the touchpad and newer manufactures would presumably have a newer touchpad. For a while my M6500 didn't have any problem so I thought I was safe. But then it started.
Dell doesn't support Windows 10 on this PC but Microsoft seemed to feel it should work, and for a while it did. But now, here are the symptoms.
If I put the computer to sleep (not hibernate) and then awaken it, then usually I can use it normally for a duration of around 10 seconds to 1 minute, and then it blacks out.
If I put it in hibernation and then awaken it, then usually I can use it normally, period. But sometimes after a duration of around 1 minute, it blacks out.
One time it was neither sleeping nor hibernating, but turned off the backlight after 15 minutes of inactivity. I pressed the keyboard's Shift key, the backlight turned on, I used it normally for about 10 seconds, and then it blacked out.
When blacked out, the hard drive activity LED still flashes, and Windows responds to a ping command, but the keyboard and touchpad are ignored. I set power settings so that pressing the power button would tell Windows to hibernate, but during the next blackout, the power button was also ignored (until I held it down 4 seconds to tell the BIOS to power off).
I installed TeamViewer. During the next blackout, Windows responded to ping, but an attempted connection through TeamViewer hanged. If TeamViewer is not running on the target PC then the client execution tells me that TeamViewer isn't running on the target, but here it hanged. So Windows really is working partially, but some devices don't work. If it were an Nvidia driver problem, why would the keyboard and power button be ignored? So something has problems but I don't think the actual cause is known yet.
I installed BitVise SSH server. During the next blackout, a connection through BitVise SSH worked. It brought up a Windows command prompt, displaying on the client machine but executing on the blacked out machine. I did a dir command and correctly saw my files and folders on the blacked out machine. I did a shutdown /h command but that hanged. I did a Ctrl+C and it stopped hanging but still didn't hibernate. I did another dir command and saw that it was still working. Eventually I pressed the power button for 4 seconds and started over.
During the next session, running normally without sleeping or hibernating or being inactive for a while, I connected through BitVise SSH again. I did a dir which worked. And then I did a shutdown /h just to check that it would work properly. It did. The M6500 hibernated. The BitVise SSH client told me the connection was lost. After the M6500 finished hibernating, I pressed the power button to wake it up, and it woke up normally. BitVise connected again, and TeamViewer connected, but that doesn't really matter because I coud use the machine normally after it properly woke from hibernation.
So the blackouts happen when something in Windows causes half its drivers to stop working but the other half are still working.
Does anyone know the real cause?
(By the way in case 240 watts isn't enough I wanted to try a 330 watt AC adapter, but as mentioned in my other thread today, the one I got seems to be a fake.)
Big news here. Microsoft describes a problem on Windows Server 2008 R2 with Hyper V, but the actual problem is a bug in Intel Nehalem processors energy saving states. Precision M6500 uses the affected processors and I bet any operating system would get confused by the bug.
Scroll down to the "Workaround" section of this article to see that the workaround avoids using the defective sleep states:
Microsoft only supplies a hotfix for Windows Server 2008 R2.
Well sure, maybe Windows Server 2008 R2 is the only one that survives long enough to record a BSOD instead of blacking out.
Does anyone know if the same workaround helps Windows 7 (same kernel as Server 2008 R2) and Windows 10?
Can Dell persuade Microsoft to supply hotfixes for Windows 7 and 10?
I set Nvidia PowerMizer Manager as shown here:
Now when the screen blacks out, everything else continues running. From another PC, I can connect TeamViewer to see what's supposed to be on my screen. (TeamViewer has an option to display a black picture on the screen of the computer being controlled, but I don't use it, and besides, blackouts occur before I try to workaround with TeamViewer.) Using TeamViewer, I can go to the M600's Start menu and click menu entries to hibernate the machine. Then I press the M6500's power button to awaken from hibernation, and it does ... to a black screen. The BIOS displays its screen, Windows displays that it's starting to boot, and then Windows remembers that it blacked out the screen so it blacks it out again. Again TeamViewer works, thanks to PowerMizer manager telling the Nvidia driver to keep running, but the blackout doesn't get fixed.
But if I use TeamViewer to reboot the PC then the screen works after rebooting.
Dell System and Device Manager says that keyboard hotkey Fn - D turns the display on or off. Well, if Windows hasn't turned off the backlight then Fn - D does turn it off or on. But after Windows decides it wants that backlight off, Fn - D doesn't turn it on again.
Usually Windows turns off the backlight after awakening from sleep, and sometimes after awakening from hibernation, so hibernation at least has a chance of not making me reboot.
But Windows isn't satisfied with that amount of strangeness. I've set Windows power management so that closing the lid does nothing. Of course it actually turns off the backlight but otherwise continues running. So far this is normal, and doesn't relate to problems discussed above. But when reopening the lid, what happens? Sometimes Windows remembers to turn on the backlight ... and displays a black screen with cursor! The internet is loaded with discussions of Windows displaying a black screen with cursor. But Ctrl-Alt-Delete doesn't bring up the blue screen with security menu ... except that if I connect another PC through TeamViewer then the other PC sees my blue screen with security menu, I can open Task Manager, etc., but only the other PC sees all this while my M6500 still has a black screen with cursor. Then I experiment again, using TeamViewer to hibernate my PC, and it hibernates. Then when I press the power button, the BIOS displays its screen, Windows displays that it's starting to reawaken, and then ... black screen without cursor. Windows remembers that it blacked out the screen but forgot that it was supposed to turn on the backlight and only display a cursor, so now it leaves the backlight off, the same as previous problems.
So PowerMizer Manager can work around Nvidia driver breakage but it can't work around Windows breakage.