M6500 blackouts, new information and question

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.)