Acer laptop wont boot

Hey, my acer laptop starts up for a couple seconds then the fan stops working and it goes all quiet, the screen remains black and nothing happens. If i put my ear really close to the back of the laptop i can hear a continuous thin beeping sound which stops upon switching off the unit. I have tried all the power drain procedures and also taken the RAM out and cleaned it. According to IT people its a motherboard problem, but I thought I ask other opinions before I buy a new one.