GTX 675MX on iMac -- only CUDA 3 supported?

Hi after much unsuccessful effort, I read somewhere that the GTX 675 MX card is only compatible with CUIDA version 3 ? Has anyone used CUDA with this card?

I have it on iMac:
Mac OS 10.10.5
CUDA Driver 7.0.29
GPU Driver 10.5.2 (346.02.03f01)

Thanks much for any help.