Prebuilt computers from the usual companies such as Gateway have shitty cooling units.
Gaming computers are usually customized with a better heatsink/fan or one of the more expensive model of gpu/cpu that comes with better cooling options.
If you open the side panel, you can peek at the gpu and see that the gpu is equiped with a tiny heatsink/fan. That is okay for light uses such as usual applications and web browsing that aren't graphical demanding.
The gpu are actually built to fail with the small heatsink/fan so that you have to upgrade or replace the unit in a few years.
Take sometime and play around with building a computer yourself. You'll learn a lot from that.
Just follow the manuals for all the wiring. It's really simple.