I am sorry you are having this problem but let me help you.
There are some troubleshooting steps you can try to diagnose or fix your issue. Please try the instructions mentioned here:
If issue persists after doing these steps, the best option would be to contact your seller or contact us for support at www.Intel.com/chat
I tried all the steps described in the link you provided. Thanks. Nothing helped. Meanwhile I got the board exchanged. But I'm having problems with the new board again. I would question my experience if I had not built the same system before.
The problems I have with the new board are different though. It boots and after running for a while it turns off suddenly. This may happen several minutes or 30 seconds after booting. It happens while in the OS (BSD) or while in the BIOS menu.
As I said on my first post, I tested the very memory module and hard disk I use in the second system in my first system (which runs fine since several months).
I want to build a PFSense firewall. I googled around and a lot of people have used this motherboard for the same system. I'm really flabbergasted why I'm having so much problems with this.
Thanks for any ideas you might have
Some more information/tests:
I disconnected the hard disk and booted into the BIOS. I watched the real time monitoring of temperature and voltages until the board switched off again - I didn't see any suspicious. Temp was well below 30 degree celsius (86 F).
Without the hard disk I noticed a high pitched sound coming from the board (it's not the PSU because the chassis has an external one). I tried again - the noise is definitely there.
One more observation. When I try to turn on the computer right after it shut down it will not start. When I pull the plug from the PSU and wait some time it will start again (but always shutting off after a few minutes).