it's almost certainly a heating problem. the gaming pushes the components,
causing excessive heat build-up by the cpu and graphics chip, which triggers
the cooling fans to run at high speeds, which in turn increases the air and
dust intake, which in turn clogs up the exhaust. it's a vicious cycle.
you can try to clear the exhaust vents by using compressed air. sometimes
that helps. other times it pushes the debris back up in the computer, only
to reaccumulate again soon. a good idea is to have a qualified technician
to do a good maintenance on it. just keep in mind that every shade tree
"computer guy" is NOT a qualified tech, so be selective.
jm