No easy solution to your problem.

NOTE: Before making any attempt to remove or replace any part inside the casing, ensure that the power is off.

Well, the first thing that might be causing this is your memory card (RAM). Try to remove it and place it in another memory slot on the motherboard.

To be sure if your motherboard is still in good working condition, remove the memory card and power on the PC.

You should hear continuous beep sounds.

If you hear this then your motherboard is fine.

If placing the memory card in another slot does not work then the problem lies with the memory card itself. You will need to replace it.

It could also be that some faulting PCI cards are causing this error.

Try to remove your PCI cards. Normally a faulting PCI modem causes this type of error. Remove it and then power on the pc.

The processor cannot be faulty but still if you want to check it, remove it and again fix it in the socket.

just unplug all the cable from cpu and hold the power button for 1 minute and again plug all the cables.if it won't work then swap the RAM into next slot and clean the dusts if any near the clips.i hope it will work....

One would need hands on access to the computer. I could be the power supply the motherboard takes different voltages than the fans. The fans on proves nothing about the power supply.

Try after changing power supply.

There's a downloadable manual with step-by-step to overcome computer cannot boot issue. It's handy, printable and it's free. http://forkus.com/docs/download/computer+cannot+boot

It will resolve the issue.

How to test your computer's power supply - The solution

Video results for how to test power supply of computer

I apologise,

I meant, I would suspect that your motherboard or any of the other device is in question.