10.5.6 is HOT
 

Hi there!

I noticed that my cpu is getting much warmer using 10.5.6. I'm using XxX 10.5.6 Final 2 actually.

In cool state after the first powering on my Opteron 185 2x2,8 GHz has a temperature of 28°C/82°F. When booting in 10.5.3 it gets after a while in idle use to about 36-38°C/97°F. But using 10.5.6 it getsin idle use to 43-45°C/111°F ! Temperature is measured in BIOS since ther's no other way on AMD cpus.

I tried various methods, removed IntelNullCPUPowerManagement.kext and such stuff. But I noticed that AppleACPIThermal.kext isn't loaded in 10.5.6. i'm actually using version 1.0.5 of this in 10.5.3, is there a newer version out there?

38C is actually pretty good for a dual-core AFAIK (thought I read AMD's recommendations were about 50C?). Try having it sneak up to 60C (yes, and even idle) like mine was before I got fed up with the stock cooler and picked up a Freezer 64 Pro. Mine was also doing this consistently across any OS so that part may not apply.
I'm not saying you should live with the temperature spikes apparent with 10.5.6 but I am saying not to panic unless the temperatures worsen. You should probably set up a CPU warning in the BIOS for when it reaches 60C just in case.
Just my two cents regarding the thermal woes. Take it or leave it.

I'm using an Scythe Shuriken, an Airtube and two case fans. It's definetively an 10.5.6 problem. I'll check why 10.5.6 isn't loading AppleThermal.kext.

Yeah, sounds like it's definitely 10.5.6, but I was just explaining that even those temperatures won't harm your CPU. I should have been more simple about it. :\
Good luck on that tricky kext. What you find out may help folks whose CPUs are actually in danger of cooking.