Bill,

 

my power supply is a 630W Be Quiet! L8.

Ok.. That rules that out.  I was thinking you might be running the very minimum PSU needed for the 680 and maybe it was starving for juice..  I'm out of ideas my friend.. 

This is really weird, maybe it´s just a "how to set the slider" thing... will try that out.

 

Jim recommended the docs... so I checked whether all Visual CC´s and MS frameworks are installed.

The guide says, you have to install MS framework from V1.1 to the latest, but I´m not able to install all of them.

Don´t really know if that is necessary...

When you say system freeze.. Describe it.. Are you saying your mouse cursor freezes, no motion on the screen, the sytem is literally frozen in place and even CTRL-ALT-DEL doesn't work forcing you to hit the reset button?

 

Edit: This may sound obvious but sometimes the most obvious solutions are the ones that do it.. Is your card seated properly? Have you tried re-seating it? Do you run any other GPU intensive games?

Card is seated correctly.

Freeze means there is no mouse cursor, ctrl alt del doesn´t work, have to hard reset via the power button.

 

Only P3D is installed.

I just checked my bios, and found something like iGPU and the primary forced graphic adapter, i disabled the iGPU support and set the primay adapter to PCIE, where the GTX is located.

 

Card is seated correctly.

Freeze means there is no mouse cursor, ctrl alt del doesn´t work, have to hard reset via the power button.

 

Only P3D is installed.

I just checked my bios, and found something like iGPU and the primary forced graphic adapter, i disabled the iGPU support and set the primay adapter to PCIE, where the GTX is located.

 

iGPU is the video hardware sitting on your i7.. That shouldn't have affected anything but you never-ever know..

 

Yeah.. A system freeze that, especially one that is re-creatable is a rough one.. Prepar3D definitely seems to be exposing a weakness in your hardware and OS setup..  Is there any crash events in the Event Viewer cluing you in on what's failing? 

 

 

The guide says, you have to install MS framework from V1.1 to the latest, but I´m not able to install all of them.

Don´t really know if that is necessary...

 

Sounds like weird advice...? I always install Windows 7 which (in my case) comes with FW3.5, update everything and then I select the optional FW 4.5.1 and that's it. But even that isn't really necessary because when you install P3D using the Setup.exe all mandatory programs will be installed or updated. I would never install all kinds of FW versions. Just like I won't install all kinds of VB versions.