You laptop has a fan, but it was probably spinning to cool down the GPU. This effect is 99.9% running on your graphics card; once everything is setup by the CPU

You laptop has a fan, but it was probably spinning to cool down the GPU. This effect is 99.9% running on your graphics card; once everything is setup by the CPU, it's all running in shaders and video memory. Still hot, but just wanted to make clear where the power is being used.