Hello Manny, the 3 beep tones indicate memory problem, but as you mentioned this can be related to the BIOS version on your motherboard.
I recommend you to first check that the RAM memory that you are using is 1333MHz at 1.5v CL9 non ECC and unbuffered.
If the memory is indeed compatible, the next step will be to update the BIOS with a compatible processor, if you don't have access to one you can surely contact our technical support and we will gladly try to assist you.
Thank you so much for your answer
You were absolutely right!
I went ahead a bought a 8GB of one of the RAMs advertised on the system board memory compatibility (http://www.intel.com/support/motherboards/desktop/dx79to/sb/CS-032853.htm) , and there you go, it booted right at first without any issues. The mobo BIOS version that I had was 406 and indeed compatible with Xeon. Furthermore, when checking the logs of the mobo, it recorded the times when I fitted the faulty ram or when I removed the cmos battery, it knew all in spite of not booting
Have been running the system for a few days doing stress check with prime95 and the cpu take it just like that.
Thanks again for the great advice
Please correct my post, I meant to say the BIOS version dispached with the mobo was 460 (and indeed compatible with Xeon) and not 406