That suggest that you did not installed driver properly, it seems that GPU is stuck at 3D clocks and voltage, try driver from driver manager (there are two proprietary drivers in Ubuntu 14.04 for nVidia maybe, choose recommended one, if fails, another etc.).
1) i used the ppa methed to install drivers i.e the first one mentioned in the guide
2)system wont reboot or shutdown was prior to driver update
hey thanks for the quick reply. i dig in a bit about the issue and it seems that i can switch between intel HD gfx and dedicated GPU using nvidia x server settings app. switching to igpu saved me the screen tearing issue and the fan speed is under control. but when switching to dedicated gpu its back to square one :(
You're welcome, i really have no idea what could be the problem, but I'm sure someone already had that problem, try to reinstall nvidia drivers (via driver manager), and wait until someone who had that problem respond.
Sometimes there are issues with hybrid graphics in ubuntu which means that it may be neccesary to disable the intel driver and blacklist it, so this guide may help. This could be the issue but I am not completely certain of it.