The CPU is "good enough" because most games are dependent on the GPU, not the CPU. However, it depends on the game you want to play since there are games that can use more than 2 cores. The Radeon HD 8670m is a bit dated though and is rather weak, it is basically in between the nVidia 910m and 920m. The Intel HD 620 is ranked within the same range.
I have an old Dell Latitude 3540 laptop with the i5-4200u and the more powerful Radeon HD 8850m which is roughly equal or slightly better than the nVidia 940mx. It serves as a secondary laptop nowadays. I kinda stopped playing games... or more precisely the only game I have been playing for about the past year is Star Trek Online (STO). Having said that, I can run Fallout 4 on my laptop...