It's all here, read and digest... http://en.wikipedia.org/wiki/Thermal_grease
Some claim that Arctic Silver improves initially, perhaps as it continues to flow into the air gaps. Presumably the better metal based compounds are more durable and the cheaper ones will eventually dry out and introduce air gaps which is not desirable. It is also of paramount importance to get the surfaces as clean as possible, a mirror-like finish is best, and there are cleaning fluids available for just that purpose.
I asking you people how long does it for you people not from the Wikipedia.
Thank for your info on Compund.
Usually lasts many years for me, but then I don't overclock or stress my machines too much! And the guys that do use their machines to the limit are probably replacing their CPUs so often they're unlikely to see a deterioration in cooling performance due to thermal paste degrading...
The quality of the Thermal Compound has everything to do with how long it will last plus whether the machines CPU is overclocked or not will shorten the life expectancy of any Thermal Compound.
We have some very good Thermal Compound available to us today with higher longevity than some of the past products that would almost bond over time between the CPU and Heat Sink, almost making it impossible to remove the heat sink.
Time wise not overclocked with good machine dust maintenance a good quality TIM properly applied would easily last 2 years and then IMO need to be changed, an overclocked machine no longer than a year.
However this is relevant to how well you keep the dust from building inside the computer, a completely dusted over heat sink seriously shortens TIM life because the heat builds too high, and literally cooks the TIM.
Regular maintenance is a habit you should develop and if you don't keep the dust from collecting and building up, the lasting of the TIM will be the least of your problems.
Too many computers end up on my repair desk simply because the owners never clean out the dust buildup, perfectly good machines ruined and have to be replaced simply for lack of dust maintenance.
Good thermal paste can last quite a while. I have been using Arctic Silver 5 for several years now. The longest I have gone without bothering to re-apply thermal paste is 3 years so far for both my HTPC and my primary rig.
I expect AS5 should last me into next year when Intel releases Haswell. At that time I will likely install my Q9450 into my HTPC which will mean I will re-apply AS5 in my HTPC next year.
My Q9450 is slightly overclocked to 3.0GHz, but the E6600 in my HTPC is running at stock speed. No need to OC that CPU just to play videos.
Been using Noctua NT-H1 for 2 years & the temp is still steady. I don't know how long it will last tho. I replace the thermal grease on my old P4 (cheap low-quality chinese grease) 2 times only from 2004 -> 2010.
Last time i used Artic Sliver 5 (require ammount) it only reduced my Temp by 10~20F
When i used Tech Thermal Grease it reduced my temp 40-60F got it from my cousin company i dont know if is sold in store and it works long as 1 year ~ 4 year even with dust. He buy alot stuff from Taiwan so that Compound must be from taiwan.