I recently built my first gaming PC, and it is a success, as well as a beast! I chose these parts from scratch because I like to make my own ideas. Coming from my dad's PC (Intel i3-3325 with integrated graphics), this is an insane step up in the world of gaming!
So far, my gaming experiences have been extraordinary. Using HWMonitor to record my temps, I have found that my CPU cooler is apparently extremely good, in the sense that under load, I have never seen the temps go above 30 degrees C. I haven't OC'd yet, so I do not know what the temps will be like then.
The case is a dream to build on. It is very spacious, allowing for great airflow and an excellent case for beginner PC builders, since you have space for cable management. It comes with many, many screws of different shapes and sizes for everything you need, including for the PSU, motherboard, GPU, hard drives, and optical drives, as well as other things that I may have failed to mention. If you need lots of storage, there are about 10 slots for HDDs and SSDs, with 2 places on the other side for 2 more SSDs. The hard drive trays can also be taken out and moved to many different places in the case. There are two slots for optical drives.
My cooling system is sufficient, with one intake 1000 rpm 140mm fan on the front, one intake 1150 rpm 140mm fan on the bottom, and one exhaust 1000 rpm 140mm fan on the back. I took out the top tray for hard drives since I didn't need it, so intake from the front is more effective. The only issue I might have airflow-wise is that my cable management for my PSU is not so good, so the bottom intake fan is partially blocked by cables, but it still seems to be effective. I also connected my intakes and exhaust fans to the fan controller on the case, so I can easily turn the fans on high for gaming and turn them low so it is quiet when I work.
As for my GPU, the most demanding game I've played has been Dying Light, with my 970 SC getting to a high of about 72 degrees C. Otherwise, games such as Grand Theft Auto V, Fallout 4, and any other game get up to a high of 60 degrees C.
Don't worry, I have seen all of the complaints about the GTX 970 only having 3.5 GB of VRAM available rather than the 4 that is advertised, but I do not believe it to be an issue at all. After some research, people have not found it to be too big of an issue, including JayzTwoCents on YouTube. https://youtu.be/v6k55epUBCE
Anyways, gaming-wise, I have been able to play most games with everything turned up as high as it can get in 1080p at a solid 60 fps, occasionally turning off Anti-Aliasing and/or Vsync for demanding games like Dying Light, GTA V, and Fallout 4.
In conclusion, I would call this the "Dream Machine On A Budget" since I didn't have a whole lot of money when I planned my parts. After almost a month of use, I can say that I will probably enjoy this machine for a few years.
EDIT: Ok, so after messing around in Garry's Mod and destroying enough wood to freeze my game, I was able to get my CPU up to 35 degrees C.