MacBook Pro does not start with RAM

Hi everyone, I have a 15" macbook pro which stopped working. When I press the powerbutton briefly, the powerlight blinks and then nothing happens. When I keep pressing the powerbutton, I hear the fans coming on, I hear the DVD drive but after a second, everything turns off, and the powerlight keeps blinking fast. If I remove the ram and I turn it on, fans turn on, powerlight turns on and the laptop beeps slowly. I also tried turning it on via the powerpads with the same result, resetting the pram, smc etc. I also tried using different dimms (the original ones) and it has the same problem. Any ideas? I am afraid that this might be something with defective RAM slots or logic board. Thanks.