Never mind - just realised that I can't run multiple copies of a game on multiple devices from a single, main pc. My idea was to have lan parties with a game running on my main PC using its processing power and a second copy of the same game streamed onto a tablet also from the main pc using the main pc's processing power. It doesn't work like that, in fact - you can only run one copy of the game on the main pc, either on the tablet streaming to it or on the pc's display device, not both at the same time, as I had originally envisaged. Sorry for the confusion.
Alienware 17 R4 2017 review