After soldering the power connector I had everything to start the first tests .... also the benchmarks had not been too bad the CPU got very hot and the system was not really stable....

I glued temperature sensors to several positions of the alu cooler and the copper blocks and used an Arduino Nano to measure the temperature at different positions.
I had teh feeling that some of teh pipes did not work correctly and asked for help in the internet. After some de-mounting and remounting, bending of 3 new heat pipes and finding that the orientation of the PC was quite important for the performance, I finally solved my challenges. Please see here for more information on the debugging:

• Englisch Forum: link
• German Forum (not as helpfull as the english one): link