ouch thats a bad thing
switch the sticks around see if it still happens.
then try 1 stick at a time.
then take the ram and try it in another system if you have it.
i doubt its the cpu infact i dont think the cpu can do that.
It's either the ram or the motherboard.

the fact that it works when you swap cpu's i THINK is becuase you have removed power from the motherboard totally.

try this.
next time it happens. power down and unplug the wall cord from the psu then hit the pwr button so the rest of the power is disipated from the board.
walk away for 10-15 min ok now come back plug in the psu and see what happens.
you may also need to reflash the bios.. i DOUBT that is whats causing it but a corrupted bios can do all kinds of wierd stuff