I slew down the details : all to the lowest, deactivated AS filtering and AAliasing.
The glitches are completely gone and i'm finally enjoying the game.
Generally, when the symptom is a CRASH, it's a game bug. When it's low performances then yes it's low hardware specs.
In this case we're dealing with a game which has just been released and with only 1 minor patch (not 1.1 but 1.01). It will surely get better.
Very n00by of the DEVs not to post the suggested settings for the typical hardware configurations. A button to test the HW and suggest settings could help a lot.
I've gone crazy after settings for 2 days, i'd never seen a game where your PC reboots...games CTD, they don't make the PC go in critical error.
Anyway suggestion to all those who have experienced a similar problem: try sliding down all the details (to the very minimum like i did if necessary) and meanwhile play and enjoy.
I'm sure BI is reading and they will come up with fixes allowing a better use of our hardware specs.