Ok, then. Which have you observed to be overheating? Is it the CPU or GPU?
If it's the CPU, you may try undervolting. I can't walk you through it, but you may learn through research. Do this at your own risk, though there isn't really any harm on undervolting if you know what you're doing.
If it's the CPU and GPU, you may try repasting. Normally, the default thermal paste used on laptops is not the best. This may cause thermal throttling when gaming. Doing this may caused actual harm to the unit. It is better if you ask an expert's help for this.