The i7 4970k has a TDP of 88 Watts, the laptop probably has throttling when on battery rather than plugged in and will likely present no issues. It also probably has a 970M or 980M graphics card, which doesn't really need a 4790K to power it unless you're using it for CPU intensive programs. The graphics card will bottleneck your CPU for 95% of games.
The laptop may get hot when plugged in and gaming, keep it away from your lap, put it on a table when plugged in. It is generally a good idea to keep all laptops away from your lap to avoid slow burns, but high end gaming laptops consume more power and thus put out more heat. Should the ventilation become obstructed by legs or a blanket, the system will heat up until it throttles itself down. Just keep this in mind since you're going to be using it for gaming.