Thanks for getting back to me with that information! :)
There are a few updates I would like you to install. Restart whenever prompted. It may take you through several restarts.
BIOS version F.24 -- Your notebook will restart on its own during the installation. Allow it to restart and get back to the Start screen.
Intel HD Graphics Driver 9.17.10.2857
Nvidia HD Graphics Driver 9.18.13.614
Intel Chipset Driver version 9.3.0.1021 -- contains the Intel audio driver
Most of those games should use the Nvidia chip instead of the Intel chip, but just in case any of them use the Intel GPU, I provided the Chipset driver version which contains the Intel audio software. Once you've completed all of those updates, try those games which didn't have sound and let me know the results when you get a chance :)