Cycles GPU render does not work I am struggling for a week now, trying my blender to work with CUDA GPU Cyclea Rendering, did so many fresh installation, still no luck.

Current situation: 

Fresh install of Blender 2.69 (from repository )
Installed Nvidia GeForce GT 640 driver from official website using text base terminal.
Installed CUDA 5.5 from official website using text base terminal.

My system:
Intel core i7, nvidia 640, OS ubuntu 12.04 64bit.

What I want to achieve:
I Want to run blender with CUDA GPU cycles rendering.
I also want to run some program which requires 32bit lib installed.

Current Problem:


Blender works fine, I can see the CUDA option but when I try to render using Cycles GPU render it does not work, no rendered image is produced.
Other program which needs 32bit lib does not work, it says it requires 32 bit lib, when I try to install that 32 bit lib it says its already there.


any help will be highly appreciated. thanks.
I had also such a problem and solved it by deselecting WITH_CYCLES_CUDA_BINARIES in cmake(-gui).

Without this blender will compile the correct .cubin file when you first try to render with the GPU. This will take a while (a few minutes on my i7), but it works.

To solve the problem with 32-bit you probably need to install glibc-devel-32bit (or similar, so called on openSUSE). There was some error about missing a header out of this while compiling blender.