The only things that have made my fans fire up is opening multiple videos at the same time, during some system updates, and strangely... whenever the screensaver comes on.
Screen saver and video I can explain.
-> It's fully GPU rendered. As much as Intel CPU's, they are nicely efficient. However, the GPU, is complete garbage in efficiency. As soon as you do anything, it goes full power 15W consumption.
Intel doesn't know how to make a GPU, let alone it's drivers. They don't have the expertise, nor looking for it. The way they see it, is to bring a new area of a mobile computing. While manufactures, sees Intel offering as a free graphic card, allowing to maximize profits or sales system at lower price point. The consumer doesn't know any better, and are content with it, ignoring the fact that it's really not good. Just NOW. Since late 2013-2014, it's adequate for web surfing and watching videos... but It does not FULLY support OpenGL and DirectX, hence why games crashes, you can visit next gen web site that aren't bare-bone like Facebook, and twitter, where if you scroll the page, the GPU can't follow up with the demand, if you are on battery, and set to Power saver, good luck playing that 1080p HD video. My 5 year old laptop, without clocking a bit faster over minimum, Nvidia very low end GPU, can handle that 1080p HD video just fine (and I would expect the same from AMD). Intel struggles. Multiple display support is half baked with Intel, and I can go on. And it's not like we don'r have the technology. Look at Nvidia Tegra K1. It's a CPU Quad core + a FULL GeForce 600 series (Kepler), together.. 5W max, and is more powerful than Intel best offering. If there was a market for dedicated GPU. I can assure you Nvidia (let alone AMD which has similar graphic solution with their CPU+GPU, which they call APU), would make that GPU alone.. so it would be what 3W? At 3W it won't even need any cooling, let alone 5W. This would allow the Intel graphic solution to be turned off, allowing reduce power consumption (which will be moved to the dedicated GPU), and even offer further gaming or 3D performance due the CPU being able to go faster for longer period of time.
Consumers need to start demanding dedicated GPU's, now you'll get a far better experience, more performance, no fan kick-in on screen saver or videos, all by keeping the same great battery life, and heat level, more or less.