When you run the computer at max you use more energy and it creates more heat.
it is the heat more than anything that will wear out a system faster. This is why there is some crazy cooling options lol.
This is also why super over clocked cpu's only run stable with liquid cooling.
When it comes to computers heat is the enemy. The more power they use the more heat is made that fast things wear out. You will also notice this if you keep an eye on cpu temp.
I have my system set to under clock the CPU (AMD Cool & Quiet) my cpu temp gets nice and low, say about 33 C. I am on an 8 core 3.6 GHZ over clocked to 4.1 GHZ. When I run anything like a game the cpu speed goes backup and my temps hit around 46 C.
This is with a 3rd party 120 MM cpu fan. This are good temps.
But if you are running a system with stock cooling you may want to see what your temps are running at. Same with the video card as well
Shane