I was testing out the limits of my new win7-64 dualboot...
I found I could load a scene of almost 5m polys into Octane inside the 1gb GTS250 and this used over 7gb ram at the end of the voxelising phase. Great!

The unfortunate thing is the viewport remained all black no matter what and it was saying and doing apparently 33msps which is crazy (broken?).

I then paused the render and tried a Live DB material. The ball came up ok with the correct mat but the view became steadily darker and darker with the rendering until it was black.

If I stimulated the render by playing with some settings it brightened momentarily but then faded to black again.
Cant really send in the 5m poly file its 360mb but seems there is a bug in the works somewhere.

Perhaps the vram is too full to have work space??? dunno....HTH