Some update from my side:
meanwhile i tested two other brand new PSUs.
Cooler Master Silent Pro HYbrid 850W
PC starts proper and seems to work well and stable. Also no problem with excessive use (Video converting and Gaming).
But if i shut down the PC or set it to Sleep0 mode after Excessive use i cant wake the PC up. Fans start to spin and sudden shut down after few seconds. Reeboot follows but no POST at all (POST numbers dark).
Enermax Platimax 750W
The PC can not start at all. Suden shut dopwn after few seconds with reboot behaviour as above.
Be quiet straighjt power 680W -> fails (sudden shut down after reboot/wake up PC)
Be quiet dark power pro p9 750W -> fails (sudden shut down after reboot/wake up PC)
Enermax Platimax 750W ->fails (sudden shutdown after switching on)
Cooler Master Silent Pro Hybrid 850W-> fails (sudden shut down after reboot/wake up PC after load conditions)
Thermaltake Thoughpower 750W (very old PSU) -> all seems to work proper.
I didnt not make all test with each powersupply. It seems that there may be an overcurrent if i start/estart/reboot or wake up the DX79SI that may lead the newer PSUs do switch of but may be ignored by the old Thermaltake.
And it seems to be temperature dependant as the Coolermaster seems to work proper at least under normal conditions.
I allwas had a look at the temperatures/ voltages with Intel desktop utilities and all leights where green so far.
Again: at least the Beqquiet problems are also present with minimum configuration (only memory Motherboard and CPU)
Nope i didnt test any of the DX79SI Intel tested PSUs as they either are not easy available in germany or they are little underpowered for my system.
Anybody and idea that may help me out?
DX79SI bundle with i7-3930k
Kingston HyperX CL9 2GB (x4)
SSD Intel 520 180GB
3 other Sata devices
Nvidia GTX 560 Ti
Win67 Home 64 bit
Bequiet Straightpower E9 680W CM
Bequiet Dark Powerr Pro E9 750W (thought little more power will solve my problem)
Thermaltake Thoughpower 750W
Enermax Platimax 750W
Cooler Master Silent Pro Hybrid 850W
Just to close this.
meanwhile i got a replacement board from Intel and all is working well.