The big silver heat sink that’s on the left is meant to be on the CPU, which is the Silver squarish shape towards the right. Keeping the CPU cool is a big deal — CPUs come with a smaller fan which is sufficient for many people, but people who use their PC more intensively, or want to extend the life of their CPU typically buy an additional cooler. Here’s an example of a stock cooler, and here’s a motherboard that’s using the fairly basic aftermarket CPU cooler that I have. It was only $30, but when I was new to PC building, it was strongly recommended, because if your CPU gets too hot, it’ll throttle itself and slow down. People who over clock their CPU (running it at a higher voltage for better performance) have to get even beefier cooling, such as water cooling. You can completely fry your CPU if you do something wrong when overclocking, and even if it doesn’t get that bad, minor mistakes can cause crashes due to CPU overheating.
So TL;DR: keeping your CPU cool is super important for both performance and longevity of the CPU.
The PC in the top photo has zero cooling for the CPU. Not even the stock fan that comes with the CPU. That heatsink that’s attached to the case fan is almost certainly intended for the CPU — you don’t even need a heatsink in that location.
This means that this person’s CPU will rapidly overheat soon after it is turned on.
Edit: you can actually see where the heat sink should match up to the CPU here










The CPU is the silver squarish shape towards the right. It generates a lot of heat when in use, so having good cooling for it is important. So important that CPUs come with a fan in the box. This involves a heat sink to help draw heat away from the CPU. This screws on mounting points around the CPU, but thermal paste is also used to help heat transfer up. Then there’s a fan that attaches to that heat sink, so that the hot air from the CPU can be blown away from the CPU.
People spend a heckton of money on cooling for their CPU and GPU, because when things overheat, they throttle themselves and performance becomes super slow. Longevity of components can also be harmed by higher temperatures. If it gets too bad, then it will crash entirely.
This PC has put the CPU heatsink on the case fan on the left. I don’t think this is especially harmful in and of itself — the big problem is that the CPU is entirely “naked” and has no cooling whatsoever. This means the CPU begins overheating basically as soon as the PC is turned on.
Edit: you can actually see where the heat sink should match up to the CPU here