That's ridiculous. I wanted to assume this was a joke but there just wasn't anything particularly funny about it.
First: computers/devices are designed to let their CPUs run at 100% with whatever cooling mechanism they have designed.
Second: PCs are a tiny minority of the devices that stream/decode video these days - especially 4K. Obviously, you don't need a 4k stream on a device that only has a 2k display or less (almost all PCs, tablets, and phones). So that leaves 4K TVs, BD players, and high end gaming-type PCs to do HEVC 4K. On the first two in that list, these days it's all done on a dedicated chip (or really, an SoC - system on a chip - that contains most of the functionality of the device. On the gaming PC, it's done on the GPU and is TRIVIAL compared to running a modern 3D game.
H.265 is going to become the standard in the near future - not just for 4K (in which is will pretty much be the only solution) but for 1080p as well, since you get significantly higher quality (including 10 or 12 bit color, BT2020 colorspace, high dynamic range, etc) for about 1/2 the bandwidth. Basically 5 Mbps to stream near Blu-ray quality 1080p movies, and even at 3Mbps 1080p looks decent. That will put HD streaming in the homes of about 90% of the US population. And that's just the first generation HEVC encoders - like X264 has over the years, they will continue to improve...