ok to clear this:

Based on scattered info, I've learned that the 1.25 and 1.42GHz Minis have different size CPU heatsinks. I read that when a person who owned one of each mini swapped the heatsink, he was able to get his 1.25 running at 1.58GHz reliably. So, depending on which Mini you own, take it easy on the overclock. It seems that the 1.25 will do 1.42GHz reliably. The 1.42s seem to do 1.58GHz reliably.

http://www.hirny.com/main/MacMini/macminimain.html

So the 1,25 and maybe the 1,33 GHz has smaller heatsink than the 1,42-1,5 GHz modells

[ Edited by Derringer 02.02.2013 - 18:09 ]