Ok, I removed all hardware, that is all drives, pci card, pcie graphics (running from oboard graphics instead). Even the RAM. Without RAM the BIOS was beeping 3 times. Put it back in, same problem. Also removed and put back the CMOS battery.
The LEDs sequence is following: dd26 - dd44 - 0021 - 0003 - 0010 and then restart.
So I'm guessing either the board or the CPU is at fault?? How can I know which? The CPU is an i7 4770 (standard, non k version)
The whole system was purchased (separately) in august 2013, but not active before october (motherboard was not available right away)