Ok i tested it again, and to be honest i cant find the cause thats why i gave it away.
It still has the same symptoms, sudden shutdown, ranging from acpi initiated shutdown wich just does powerdown with saveing data, to an spontan powercut wich means power loss and bootup with a warning from windows.
Either there is a event 109 or event 41 in windows event manager.
It is not software related it can happen at bootup aswell. Or in Bios or on a Linux cd.
The ram was...