unable to use NVIDIA card

I have a acer laptop with a NVIDIA GT 55M, which is not used by Ubuntu. Indeed in system setting it tells "Gallium 0.4 on llvmpipe (LLVM 3.6, 256 bits)" which I assume is the integrated graphic card.
While it's ok for a low usage, it's really bad playing videos, even with a poor 720p .

I'm not sure if the problem is about drivers, settings, or whatever. Trying to have it working I played with drivers, grub configuration, optimum and prime, but it still doesn't work.
According to system setting I'm currently using NVIDIA binary driver - version 352.63 from nvidia-352-updates.

Any help would be really appreciated.

I can post output of a few commands, but I'm sure that there are many that I don't even know. Just ask and I'll try them and add their outputs.

$ lspci | grep 'VGA'

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: NVIDIA Corporation GF106M [GeForce GT 555M] (rev ff)

 
[ 3289.867707] [ERROR]Caot access secondary GPU - error: Could not load GPU driver

[ 3289.867864] [ERROR]Aborting because fallback start is disabled.

** Message: PRIME: No offloading required. Abort
** Message: PRIME: is it supported? no  

/**Other stuff not relevant**/