SOLUTION FOUND!!!
I looked at ASUS Sabertooth 990FX specifications and found they are using JMicron JMB362 controller for the SATA 3Gb ports, which I think is the only 2 ports of this type in my Board and used by these 2 Optical Drives (I feel lazy to open case and tell you exactly, but I'm sure is where I plug them), anyway. I went to:
http://en.wikipedia.org/wiki/JMicron
"...JMicron's JMF601 and JMF602 SATA flash controllers were reported to have issues with write latency, causing a stuttering problem.[5][6] The performance problem was attributed to the small buffer size used in the controller..."
After reading this I went to JMicron site.
OK, my detective quest is over. Finally I found the problem and it was this JMicron controller that ASUS is using in its Motherboard. It has a write issue making the PC crash. I went to JMicron website and download their lastest JMB36X drives which date from 2012 and these optical drives start to burn disks. This brings to my attention that ASUS is not doing their work right. Under > Support > they're offering chipset drivers updates (AMD Chipset Driver V8.973 (8.0.877.0) for Windows XP/Vista/7 32bit & 64bit.) but they should include driver for all the component they are using on their boards...
Anyway, kind of pissed with ASUS for this big mistake, but happy to finally fix my problem.