I have a late 2010 Macbook Air w/ 2.13 Core 2 Duo , 4GB DDR3, and 256SSD that came from the factory... and the heat and fan noise generated whenever using my mac to watch any kind of online streaming (youtube, videos, or playing mpeg4 Videos) would have the fans kick in to 6500rpm within a minute or so (iStat was registering the CPU temperature at above 90C, where it would be idling at 65-68C when not watching any kind of videos).
I eventually caved in, and decided to order the necessary screw drivers / bits to open up my macbook air and have a look inside. Was reading alot about how poorly the cpu's thermal grease was applied, and how others were reporting success. I tried the pram and smc resetting, but noticed no difference before or after.
Before redoing the thermal grease on my CPU / GPU my Temperatures reporting with iStat showed the following...
(no web browsing i.e. no emails, nor reading online...): Idle Temp 52C
(Web, reading emails, online, but no flash or streaming): Browsing Temp 68C
(Watching online streaming or playing MPEG Videos): Streaming Temp 92 - 95C
After applying thermal grease on CPU and GPU: 38*C / 46*C / 72**C (streaming within a window sized screen) 82***C (Streaming Full Screen).
Respecting Fan Speed:
* = 2000rpm steady
** = 3000 - 3250 rpm mildly varying below 3000rpm (can't hear it)
*** = 3800 - 4200 rpm variable (need to listen for it to notice it, but late at night with earphones on, I do not disturb the person sleeping next to me).
Before, I could not stream any kind of video without the fans kicking in and whurring away at 6500rpm.
I was planning on replacing my macbook late 2010 air, but after this very successful mod, I love it all over again (more than my 15" macbook pro retina).
Cheers,
LormaD