in experience extreme heat or overclocking causes it.
make sure you are choosing to use the win 10 drivers, (not the beta)
- not the old ones if you had previous ones installed from say the same windows but 8 update to 10, then you need to do a clean install(manually uninstall the old driver and then delete folder in system C:\Program Files (x86)\NVIDIA Corporation)(so it dosent grab the WinX ones first) , and run a reg cleaner such as ccleaner. and then restart download and reinstall again.
check the games make sure they fully support win10.
by now the nvidia drivers are very stable in windows 10 so there must be a conflict somewhere else...
when you look for drivers dont look for 740m series just look for gernaral 700series , you may be blocking the heat output in you laptop,maybe vacuum the thing out( while it's off) and if you have it on your lap put it on a hard surface like a board.