For quite some time now, we've seen some issues where the computer is shutting down from an overheated PSU (Power Supply Unit) or it is dieing too soon. This is in part due to modern case designs. Not that it's defective, but I guess you can say it's a combination of factors.
If you'll notice in the past, PSU placement in the case was usually above the motherboard. With this design, it would be pulling warm to hot air into it, which can lead to early failures of the PSU. These days, most of the newer cases have the PSU placed at the bottom of the case. These cases were designed with vents at the bottom of the case so that the PSU can pull cool air directly from outside and blow out to the rear.
The problem with this design is that if the computer is placed on top of thick carpeting, it can block the vent and thus suffocate the PSU. There is usually a small gap in between the PSU and the case so that the PSU can still pull air from inside the case, but sometimes that is still not enough.
So, just a word of advice, if you get a bottom mounted PSU case with vents on the bottom, try not to place it directly on the carpet. If you still want to place it on the ground, place other items to stand it on just enough so that there's a gap between the carpeting and bottom intake vents.