Hello,

facing a "fan always blowing" issue on a Dell D420, I did a few
observations with various OS to see how cpu speed and system temperature
were linked.

as expected, when the cpu runs slower, the heat is lower... :)
the thing is I still get a 10°C difference between running NetBSD and Linux.

on NetBSD 4.99.16 and 4.0_BETA2, setting the speed to 1200MHz keeps the
system at about 57°C (I let the system idling until every the three "Load
Averages" values were 0.00) and setting it to 800MHz keeps the system at
about 54°C.

on Linux (2.6.x from XUbuntu 7), the temperature went down to 48°C since
it ended booting from the live CD (the laptop was at 57°C from the
previous NetBSD testing). after waiting a bit (about 10min), the
temperature went down to 46°C.

on my testings, NetBSD stayed in console where as Linux had Xorg up.

I tend to think the Linux values are true because it seems the fan runs a
bit slower... that's initialy why I decided to keep numbers to be sure it
was not just the environment noise fooling me...

my question is: how can one explain this ~10°C difference ?

I kepts a few informations (dmesg, lspci, ...) here
http://www.tumfatig.net/dmesg/Dell%20Latitude%20D420/ if it helps... Maybe
NetBSD don't really match the lowest possible speed on this cpu ?

Regards,
   Jo