Help!! my mobo is bricked very often

[hil4552]

I has this system
i7 920 3.6 @1.2 V every other voltage set to auto
BCLK 180
ASUS Rampage 2 Extreme
2*3GB geil ram
gtx 280
9600gt(run as physic card)
creative sound card
Thermal take 1000W psu

It worked flawlessly for me for about 1 year until last month, it just didn't boot. what I mean is all led on board seem to be working fine but when I pressed power button nothing happen psu didn't even start. so i rma the board. when i got new one everything seem to work fine, my game run fine. not a single problem. But a week later same problem, it didn't boot. Ok I think i was just bad luck so i rma it again, however today same problem happen once more. Just to let you know that i have already clear cmos unplug everything then put only cpu 1 ram and a gpu but it still doesn't work. Also before the problem occur everything seem to be normal no crash no, BSOD. I just shut down it normally then the day later it just refuse to boot

I sure it is not coincident that my mobo brick with the same problem so i think on of my component might cause it. what component do you think is most likely caused the problem?
sorry for my English i am not native speaker

 

[o1die]

Don't rule out the power supply; any brand can fail, even the better ones. Also check your backplate for metal to metal contact with your motherboard ports. Some have to be bent or broken off to work; may have some leftover metal making contact somewhere on the motherboard. Also check your case standoffs to be sure they line up; remove any that are stripped or out of position with the motherboard mounting holes.