PhysX vs Havok/Similar

[aIW|Convery]

Good morning all,
so while trying not to turn this into a AMD vs. Nvidia thread I need some advice.

I've decided that I'm going to replace my laptop with a desktop and due to my limited space I'm going for a mini-ITX format one. Sadly mini-ITX only got one PCIe x16 slot and therefore I need to choose a single graphics card.
Now, I've tried to google to find info but I couldn't find anything relevant.. I'm currently looking at a GTX 570 or a 6970 for it but I wonder if GPU accelerated physics will be the best option in a single card setup.

For this build I'm getting a intel 2600k CPU which should be able to process the physics calcualtions need for a game. However I've heard that Havoc and similar uses 8 threads and therefore wouldn't leave enough for other aplications to run at optimal levels..
The downside with GPU physics would be a drop in FPS and they lack support for many games so I'm not sure it's worth getting just for that feature..

So should I go for the Nvidia one with lower frame rate or the AMD and hope that my CPU can handle it as good as the GPU would? (can't overclock on this chipset)

[Alen]

Tbh you never use any sorts of physics when playing, and if you do (very small chance), it's usually just some minor effects. Trust me, you'll survive with CPU-calculated physics