PS. Windows 7 64 bit installation seems normal but beeps are also without HDD, so these can't be ops system dependent.
There isn't listed any Beep command in POST table, so these beeps are alerts and not normal.
Mem test revealed that there doesn't seem to be any memory issue.
Network boot has been disabled.
The question is still without reply and the PC is waiting it's verdict.
I obtained a POST tester but there is not help with it.
The first beep occurs between 60 and following 5E and second beep when there is 90 on display second time. and following is final POST 00
Any of the 3 codes doesn't seem to be mentioned in motherboard user manual.
I obtained and changed also memory to different type. Replaced USB keyboard.
Updated BIOS from 040 to 044, but no changes.