Game gets unresponsive after playing for 10 to 30 minutes

[nebej]

As you say the game is not suppose to crash when you run out of VRAM. It should just swap with normal RAM and there might be some framedrops.

I have passed this info to our Nvidia contact.
Our Mac porter found a similar issue on some mac computers with nvidia. He said that it was an issue with the driver so it is most likely the same here.