yes it will shorten our cpu/gpu/ram lifetime.

but how short it will shorten it into?

a NORMAL lifetime of a computer hardware is 10year(there are still some P2 and P3 era hardware working out there) so u can estimate how long a computer hardware can live

from 5 year lifetime to 3 year lifetime?
A normal processor operation temp is 40-60°C some even 70°C and a Overclocked processor with a 3rd Party cooling normally will get 50-60°C some even LOWER with water cooling.

so, normally, a 1.8Ghz to 2.5Ghz is counted as light overclocking it can increase 5+- fps which CANT REALLY U CAN FEEL IT

normally, Overclocking is just done by computer enthusiast for the purpose of getting higher score in benchmarking program...

ya, i still have an Pentium(Pentium 1) proc which still can use, but i cant find anyway to format it(dont have win95, so i destror the WORKING mobo and keep the proc