|Failed Powersupply, Failed Heatsink fan, Failed CPU, Failed motherboard, Failed ram, Faulty PCI card, Faulty drive (HDD and/or Optic drive) Faulty USB device. |
Simple things first. Does the heatsink fan spin when you try to bootup?
With power disconnected, unplug all power and data cables from harddisk drives and optic drives. Remove any PCI cards, Remove all but 1 stick of ram. Leave only motherboard, CPU with Heatsink fan, Graphics card, 1 stick of ram and keyboard. Reconnect power and see if it will boot into bios and give any POST beeps. Report back when you've tried this.
I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.