Almost 10 days later, I confirm : no issue discovered with this Bios.
I even thought it was fixing a bug in power management... but unfortunately no : the bug is still there.
The bug is that sometimes, after power management switches off the screen, it's no more possible to have it up again. All is working, keyboard, drive, sound, etc..., but the screen remains black. The only solution is to force sleep mode (hopefully, fn+F1 makes that possible without seeing anything on screen), then wake up the pc.
And this bug doesn't come on a "fresh" windows session. I never stop Windows, but make "hibernate" my Pc (Hibernate="Veille prolongée" in french. I don't remember english word). And after several days (1 at the worst, 10 at the best, it depends), the bug comes.
And after sleep/wake up to get again pc control, I restart the Pc, and it's OK again for several days.
Does anybody have beginning of an idea ?