Have you tried the memory by switching them around or a different set.
Yes, I've actually switched the sticks and tried them singularly on three different slots (the fourth is unreachable, with the CPU fan mounted). Unfortunately I don't possess another set of DDR3 RAM sticks, but how much is probable that the two sticks died at the same time?
Anyway, in order to figure out the problem, I desperately tried to remove every peripheral connected to the motherboard, one by one, but the problem is not gone. The only ones that I didn't removed yet are the CPU and the PSU... how can I understand whether they're failing or not? The really short troubleshooting section of the motherboard manual says that if the CPU cooler works (and it does), then it's not failing. Is that really a sufficient condition?
So, since the disconnection of every peripheral doesn't solve the problem, do I have to assume that the CPU, the PSU or the motherboard itself are failing? I really don't know what to think, the PC is very much young and it was working smoothly, then suddenly this problem appeared. Do I have any hope clearing the CMOS values?
If it can be anyhow helpful, I even made a video:
http://tinypic.com/player.php?v=2isfgnt%3E&s=5#.UtUhsNLuJA0The worst thing is that I really can't find a description of the meaning of this damn beep code, not on the manual nor on the Internet.