So... Next day, next try. The chipset driver is the latest, same as before, restart.

Now i had loaded Speed Fan and tested it. Alle the values, CPU etc, are low. Temp1 and Temp 2 are on 27-31c. HD3 is under 30c, too. CPU is constant on 14c. Sometimes it goes a little bit higher but not over 20c. All others are 0c.
The only value that goes higher and higher is the GPU. Test it three times and it allways restart the pc when GPU is on 102c oder 103c.
I do nothing ingame when i check the values. Only stand in Uldah and do nothing.
Then i try to run the FF-Benchmark and it was the same, shut down at 103c.