does anyone experience hardware overheat in ubuntu

[thirstyh2o]

I'm running Ubuntu on my Dell Latitude d820 starting from Feisty to 
Gutsy, then Hardy from which I finally upgraded to Jaunty (necessarily 
through Intrepid).

Several days ago I decided to give Debian a try and installed Lenny as a 
dual boot to my Jaunty on the very same laptop.

While I'm not totally happy with Lenny (or better to say, not totally 
happy with it YET), I run across an unpleasant surprise about my Ubuntu 
too.

I found out that my laptop (CPU, HDD, and video card) always runs under 
well higher temperatures under Ubuntu then under Lenny.  And the numbers 
differ quite significantly. 

My CPU temperatures under Ubuntu are always between 45 and up to 58 
degrees Celsius. It actually drops sometimes down to 40 too, but it's 
quite a rare case.

Surprisingly enough under Lenny the CPU temperatures in several days 
never came over 37 degrees Celsius as its very maximum. And this is the 
rare case too. Normally it runs between 32 to 35 degrees Celsius only.

Thus when I'm running Ubuntu my fans are almost constantly on. And when 
I'm running Debian Lenny they are almost constantly off. And, if you are 
curious, my palms confirm the results too. :-) I mean I can really feel 
the difference touching my laptop.

The measurements are taking using the same tools under both OSs: lm-
sensors, i8k, etc.

The only significant difference between installs for now are video 
drivers for my Nvidia card: Vesa under Lenny vs. restricted under Ubuntu. 

Any comments/suggestions, please?