well, processors are quite durable components, so the decrease in life is quite minimal, if noticeable at all.
also, most of the electrical components can stand up to 5years of continuous operation at 105oC, which is the worst case scenario. Imagine then instead of operating at, say, a stock temperature of 40oC which increases to 50oC when stressing, I now operate at 50oC which increases at 65oC.
If my components are of good quality they will go on for more than 10years.
Anyway, usually what I notice to break sooner than everything is the power supply, which usually takes all the "bad" energy from the mains and degrades slowly over time.
My CPU at home, a Pentium D, is 5-6 years old, overclocked with a crappy motherboard, and is just on the edge of giving up, because the power supply cannot handle power so good any more(have a 650W coolermaster and the fan is at full all the time, which I figured It means the heat in there is quite high, which it shouldn't, because such a system would use around 200W-300W max) and the motherboard is glitching slowly.