Yep, that's right.  Octane only works with Nvidia CUDA enabled graphics cards, and the better Nvidia card, the faster Octane will render.  Nothing below the GTX line would be recommended, and it must be CUDA enabled.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.