The darn thing working fine one day
Attempted to switch on following day and the only sign of life is three lights, namely capslock, numlock
and direction key lights.
Screen is blank, floppy drive won't work, cd drive won't work, cpu fan isn't running.
If left on cpu overheats.

Anybody got a clue?
model is compaq armada e500s

I've got the same problem, but in this case the fan is working. Just get a blank screen, three green lights (numlock, capslock, and the one next to it). Machine is Compaq Armada E500.
I don't have a solution (yet), and your message was posted a while back so doubtful if this thread will reach a satisfactory conclusion.

I had this problem after I replaced the mobo on my Armada 7400. After scrambling to find the solution, I came across these posts.

For me, my HD would not spin up however the three lights would illuminate, and that was it. The solution in my case was that I forgot to put the ram back after I swapped boards. After I put the ram in, it booted up gloriously.

My suggestion to you guys is to check your ram--be sure it is seated properly and works. Maybe, if you have spares, swap it out with a different stick and toggle which memory bank it is installed in. Maybe the ram port is bad.

To the person who put in and took out the sound card--could it be that this re-seated the ram stick the first time you did it?

Best of luck.