Precision 650 don't boot... 1-2-3 error code, Amber-Amber-Green-Green leds ON

When i connect the power cable the A Led goes to Amber inmediately, then when i turn on the Presición won't boot, and I have 1 -2-3 beep codes and then i got on amber the A and B leds on.

I tried changing the memory modules on the other slots, but the same problem come, y change the memory modules for diferent ones, but the problem persists,

What could be my problem? is it the memory? is it another thing? Please HELP ME!