..Fortunately, was just a nightmare. Everyone can use OpenCL, old macs (as my macbook) cannot use GPU, and cannot run faster, but OpenCL code can run on every machine.
You (as developer) need just to keep in mind to get Device in this way. So, if you haven't the latest NVidia you can still use, as always, CPU.
err = clGetDeviceIDs(NULL, CL_DEVICE_TYPE_GPU, 1, &device_id, NULL); if (err != CL_SUCCESS) err = clGetDeviceIDs(NULL, CL_DEVICE_TYPE_CPU, 1, &device_id, NULL);