PowerMacs G5 run at full speed. PowerBooks, iBooks and Minis do not.

OSX is constantly switching the CPU frequencies, while MorphOS is running at max speed, so in the result both CPUs are getting hotter. One CPU is getting hotter than the other because the cooling fluid is flowing from one (the cold one) to the second, which gets the already warmed up fluid from the first CPU.

As the temperature is in general higher than when using OSX, the fans are running faster and producinig more noise.

If you compare two identical models with MorphOS and one is silent, while the other one is making your ears numb, then there is an issue with the cooling, the sensors or the cpu. This can be dust on cooling plates, a tollerance in sensors/cpu, a not so perfect contact of the heat pipes and the chips and of course the cooling liquid that should be replaced and the water cooling may need a clean from the inside.

So even with two fully reworked G5 running at the same speed, it is possible you never get them equal in noise output.

Geit

PS. Same of course for the FAN only versions of course.

[ Edited by geit 03.06.2013 - 11:05 ]