My computer is rather slow (too slow for my needs but I must make do for a while). It has an atom n270 1.6Ghz FSB 533Mhz and GMA 950. The problem is that it plays 720p H264 videos fine but cannot handle 1080p. Even overclocked 1080p does not play properly. So sometimes when I only get the content in 1080p, I have to first convert it to 720p. At stock speeds the conversion speed is 1.5FPS and this takes really long. Overclocked I can achieve 5.2 FPS (Still slow but much better!) If I overclock as follows using the same voltages CPU 2.0Ghz FSB 667Mhz (The Ram supports up to 800Mhz but is limited by the CPU) GMA 950 to 400Mhz Note the Gma 950 chip in desktop and laptop is the same. However to save power in the laptop it has been manufacturer downclocked to 166Mhz, I just restored this to 400Mhz. Will this reduce the system lifespan? I have modded the cooling and under load overclocked CPU is at 60-63 Celcius Motherboard is 72-74 celcius.
Any overclock can reduce the hardware life, further about the temperatures that is high for one low performance computer. In the maximum with overclock, your PC can't exceed the 50ºC for the CPU and Motherboard. If you need of any overclock, in a first moment is needed of refrigeration and power supply to maintain stability about the temperature on the computer. High temperatures also can be a problem of the power supply that isn't providing the necessary supply in overload.
The maximum safe temp is 90 for this cpu and 85 for the motherboard. It is always above 50 C even when not overclocked. This CPU is supposed to get rather hot despite being a low performance cpu.