I edited this to make it easier for other people with similar problems to find:

Win 7 x64
i7 3820
16GB
2x7850OC X-Fire
X79-UD3

The situation:
Game freezes entire computer every single cutscene, sometimes during gameplay. I can normally only get 20 minutes gameplay in before it freezes. It can't make it past the first flashback scene with Geralt running through the forest. A hard reset (holding down the power button and forcing the computer to shut down is required to fix, ctrl+alt+del does nothing, ctrl+shift+esc, alt+tab do nothing. My entire computer would freeze.

UberSampling ON stops freezing
Disabling X-Fire also stops the freezing.

These two fixes may allow me to play the game, but it was not ideal because I wanted Ultra at 60fps. That's why I spent money on the second card. I tried updated/rolling back drivers, edited things in the registry, etc.

I started played with Ubersampling on, and once Foltest died, I was in the dungeon waiting to escape, the framerate jumped to around 70fps (the dungeon was such a small area to load), and my game started crashing again.

So I figured what was causing the crashes was a framerate higher than the refresh rate. Ubersampling and disabling X-Fire was not a fix, it was a just a workaround the problem.

So I set everything as I'd like, and simply enabled V-sync this time. And the game runs like a charm. I already made Flotsam after an hour and no crashes as of yet.

Hope this helps you.
Josh.

tl;dr:
Framerate higher than refresh rate caused crashes
Disabling US and Crossfire was simply a workaround.
Simply enable V-Sync.

In the options settings in the launcher, try selecting the 16:9 aspect ratio.

I'll try finding a older version of AMD drivers, and I'll report back whether it works or not.

I've already tried changing aspect ratios, none of them make the game run properly.

Edit Above

Edit Above