GForce GT 635M in hp laptop blank screen after startx

With the above hardware, after installing v384.59 of Nvidia display driver, running startx does not switch to X. XOrg log says that only CRT-0 connected and does not list any other screen devices such as HDMI or lvds. No efi, no selinux. Kernel driver reported as successfully loaded, but no X. Bios does not allow intel graphics to be disabled. Any suggestions to fix this problem? Thanks.

NB after startx from another terminal run DISPLAY=:0 glxgears &
Then nvidia-smi reports an increase in its temperature so there is it appears the driver is functioning, but just not showing anything on screen.

It’s probably an Optimus laptop, see here how to configure:
http://us.download.nvidia.com/XFree86/Linux-x86/319.12/README/randr14.html
https://wiki.archlinux.org/index.php/NVIDIA_Optimus
Other that that, run nvidia-bug-report.sh ans attach output file.