Test Your Gaming Rig Assembly Skills With The Immersive PC Building Simulator
It's called PC Building Simulator and it's available now to tinker with, albeit as an alpha build. As such, it's a bit rough around the edges. The only mode of play is the tutorial—there is a career mode visible, but it is not yet available to play.

"The purpose of this game is to try to teach people about building PCs while still having fun," developer Claudiu says. "I strive to make it a fun game to play but also a tool to plan builds for those who want to practice this hobby without spending thousands of dollars."
Claudiu's concept is spot on, as this is just the kind of thing that's needed for hesitant first-time builders to make that leap into do-it-yourself (DIY) territory. However, as would be expected from an alpha release, it needs some work. We played around with the current release and found that it can be a bit finicky at times. There is a sweet spot for certain actions—it was especially tricky trying to open the clips on the DIMM slots.
The simulator would also benefit from more modern components, along with a bigger selection of parts. You only have access to a 500W power supply, though you can install two graphics cards. Claudiu is aware of this and says right now he's mainly focused on getting everything to work. He promises to add "numerous 3D models" in the future.

These are all issues that can be hammered out. Even with them, this is an impressive simulator for a one-man operation. Hit the source link if you want to try it out for yourself.