i just have a laptop right now but i do plan on eventually building a new pc.
but before then i had a first gen core i7 that lasted me more than 6 years and it would have gone longer if i decided to keep it. if i were to build again i would get something in the higher end area for my cpu/mobo. a good one should still be able to game on effectively in at least 5 years. gpu on the other hand, have to be replace much sooner than that.