Update the BIOS again using the Q9550 processor using the BIOS recovery method, then check how the processor is reported using the Intel(R) Processor Identification Utility.
Furthermore, what is the part number and manufacturer of the memory sticks you have tested with?
What is the wattage of the power supply installed?
Have you tested disconnecting as much peripherals and add in cards as possible?
Problem SOLVED! I updated my bios (v572) again with BIOS recovery method (cd + .bio file) and everything is working great!!!
Thanks all of you!