GTX 650ti stops working

Hey gus, I am having a little problem with my very new GTX 650ti. When I have about six million vertecies in my scene, blender will not render the image, but leaves me with this error message: Cuda error: out of memory… Now I know that this is a problem with vram, but my older GT 360 renderred with a higher amount of vertecies. Can someone help me out?

Hi, you give not much information to us.
How many Vram the 550 has.
Cant find a GT 360 anywhere > https://developer.nvidia.com/cuda-gpus
Did you you use the same Blender version to test, when yes which?
OSX, Linux, Windows? and which exactly?
Six million vertices is very much even for a very detailed scene.

Cheers, mib.