Computer powers on.. but doesnot work

Hello,

My computer stopped working a couple of days back. The power supply was working properly but it's not turning on. So I tried to solve by re-assembling. I assembled the processor and the processor fan and tried to turn on, now the computer is turnin' on.. It's simply working, nothing is going on.. Not showing any beeps or anythin' that the RAM is not inserted... I tried inserting the RAM, Harddisk and all.. But it's not working.. The processor fan is simply running.. Monitor goes to power saving mode..