need help for mint 17 qiana + geforce gt 630

Hi, there

another noob that can’t manage to run cuda in blender.
Here are some infos for you:

PC: Intel® Core™ i5-4670 CPU @ 3.40GHz 64bit
OS: Linux Mint 17 Qiana MATE (Ubuntu 14.04 LTS)
Graphic card: GeForce GT 630
Drivers: found a 352-version in the additional driver window, but after installing nvidia modprobe it automatically changed to 340.
I have blender 2.71 installed from somewhere, but i use the portable, newest version (2.76).
No, there is no cuda option under [user preferences→system].
Yes, i’m using cycles. Yes, i also tried “experimental” in the render tab. Yes, i think i even found the right version for modprobe out there - at least in the synaptic manager i can find the version entry 340.
Maybe this is interesting too: I install my applications in a separate root account, while normally i use a restricted user account. I think this safety concept is called “sandbox”.

Here’s what i get when i paste [sudo dpkg -l | grep -i nvidia] in the terminal (as someone somewhere asked someone to do, but i don’t understand why and that bothers me nearly as much as the fact that my graphic card doesn’t work out of the box as it should in my opinion. Is my frustration noticable? Sorry.):

ii bbswitch-dkms 0.7-2ubuntu1 amd64 Interface for toggling the power on nVidia Optimus video cards
ii libcublas5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA BLAS runtime library
rc libcuda1-331-updates 331.113-0ubuntu0.0.4 amd64 NVIDIA CUDA runtime library
rc libcuda1-340 340.96-0ubuntu0.14.04.1 amd64 NVIDIA CUDA runtime library
ii libcuda1-352 352.63-0ubuntu0.14.04.1 amd64 NVIDIA CUDA runtime library
ii libcudart5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA runtime library
ii libcufft5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA FFT runtime library
ii libcufftw5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA FFTW runtime library
ii libcuinj64-5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA INJ runtime library (64-bit)
ii libcurand5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA Random Numbers Generation runtime library
ii libcusparse5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA Sparse Matrix runtime library
ii libnppc5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA Performance Primitives core runtime library
ii libnppi5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA Performance Primitives for image processing runtime library
ii libnpps5.5:amd64 5.5.22-3ubuntu1 amd64 NVIDIA Performance Primitives for signal processing runtime library
ii libnvtoolsext1:amd64 5.5.22-3ubuntu1 amd64 NVIDIA Tools Extension
ii libnvvm2:amd64 5.5.22-3ubuntu1 amd64 NVIDIA CUDA Compiler NVVM runtime library
ii mate-sensors-applet-nvidia 1.8.0-0+qiana amd64 Display readings from hardware sensors in your MATE panel (NVIDIA sensors)
rc nvidia-304-updates 304.125-0ubuntu0.0.1 amd64 NVIDIA legacy binary driver - version 304.125
rc nvidia-331 331.113-0ubuntu0.0.4 amd64 NVIDIA binary driver - version 331.113
rc nvidia-331-updates 331.113-0ubuntu0.0.4 amd64 NVIDIA binary driver - version 331.113
ii nvidia-340 340.96-0ubuntu0.14.04.1 amd64 NVIDIA binary driver - version 340.96
ii nvidia-340-uvm 340.96-0ubuntu0.14.04.1 amd64 Transitional package for nvidia-340
rc nvidia-352 352.63-0ubuntu0.14.04.1 amd64 NVIDIA binary driver - version 352.63
ii nvidia-cuda-dev 5.5.22-3ubuntu1 amd64 NVIDIA CUDA development files
ii nvidia-cuda-toolkit 5.5.22-3ubuntu1 amd64 NVIDIA CUDA toolkit
ii nvidia-libopencl1-331 340.96-0ubuntu0.14.04.1 amd64 Transitional package for nvidia-libopencl1-340
rc nvidia-libopencl1-331-updates 331.113-0ubuntu0.0.4 amd64 NVIDIA OpenCL Driver and ICD Loader library
ii nvidia-libopencl1-340 340.96-0ubuntu0.14.04.1 amd64 NVIDIA OpenCL Driver and ICD Loader library
ii nvidia-modprobe 331.62-0ubuntu1 amd64 Load the NVIDIA kernel driver and create device files
ii nvidia-opencl-dev:amd64 5.5.22-3ubuntu1 amd64 NVIDIA OpenCL development files
rc nvidia-opencl-icd-331-updates 331.113-0ubuntu0.0.4 amd64 NVIDIA OpenCL ICD
rc nvidia-opencl-icd-340 340.96-0ubuntu0.14.04.1 amd64 NVIDIA OpenCL ICD
rc nvidia-opencl-icd-352 352.63-0ubuntu0.14.04.1 amd64 NVIDIA OpenCL ICD
rc nvidia-persistenced 331.62-0ubuntu1 amd64 Load the NVIDIA kernel driver and create device files
ii nvidia-prime 0.6.2linuxmint1 amd64 Tools to enable NVIDIA’s Prime
ii nvidia-profiler 5.5.22-3ubuntu1 amd64 NVIDIA Profiler for CUDA and OpenCL
ii nvidia-settings 331.62-0ubuntu1 amd64 Tool for configuring the NVIDIA graphics driver

If there is any other info missing to have a clear view on my problem - please let me know.