Firstly my front usb's stopped working for a day, no other problems at all b4 this. Then i was away for a few days (computer off) on return computer would not boot. no beeps. no post, just fans and black screen. I tested the two ram modules and both have some led lights, i tried taking one out/ then swapping them etc no difference. I thought then it was the mobo, i replaced it w a (untested) secondhand mobo. This time fans start for a moment then stop, still no post no/black screen etc. I tested the power supply in another mobo/old sys and it powered up and there was post sound. I have now found that the fans work when the 4pin atx12v is not plugged into the board. as this powers the chip i am wondering if the chip is fried or if it may be something else?