Even then, if a commodity chip isn't pushed full tilt at all times, and assuming that the venting and dissipation are adequate, a commodity chip can last a long time.
Except you can overclock v3 :)
Bearings in fans, caps etc. are also stuff that you need to keep an eye on.
I just replaced a i5-660 thats been powered on since 2010 24/7, heatpaste was fucked so it crashed during heavy loads :)