Alex wants to build his own computer. Leo says that building his own PC is a good exercise and he'll learn a lot about how a PC works. He won't save any money doing so, though. And if there's something wrong, there's no one place to call. He'll have dozens of different parts and the manufacturers will just pass the buck. So he'd end up being his own support.
building a PC
David's old PC that he built has crashed. He wants to know if he should build another one. Leo says that building your own PC really doesn't save you money anymore. It's far more efficient to just buy a new computer from Dell or another manufacturer. That way if there's an issue, David would get support. When he builds his own, he is his own support.
Brad built a computer running Windows and now it just shuts down while he's still using it. Leo says it sounds like a bad power supply. Brad replaced it, though. Leo says that's the downside of building his own machine -- he'll have to hunt down the problem himself. Leo suspects that since the power supply didn't fix it, the motherboard is probably the culprit. It could have been from a power surge. He should try replacing the battery for the BIOS and see if that resets it. If that doesn't work, it could be the motherboard. The next thing to address would be the CPU.
Mike has been watching Leo's VR Computer build and he wants to build his own PC as well. He's currently running a 6 year old Intel Core 2 Duo computer, but he's upgrading the video card so that he can play 4K video to his TV. Leo points out that he could run the Oculus Rift on the GTX 970 video card that he has as well. He's planning on upgrading the computer to the Intel Skylake i7 processor. He does a lot of transcoding, which is very CPU intensive, so that's why Mike needs a high end computer. It can be GPU intensive too, but modern Intel platforms do quite a good job with video codecs.
JR has been a Linux guy for about 20 years exclusively. He's building a new computer with a fixed budget. Leo recommends going to PC Perspective's website and on the menu bar they have the HWLeaderboard. The Hardware Leaderboard lays out price ranges for building your own PC and what components you should get.
If he sticks with Linux, the issue will be drivers. The good news is that Steam is using Linux for their Steam Machines and as such, Linux support is growing.