Thanks for replying.
The power light remains constant.
There is no beeping from the system now, this only occurred when I had removed some components.
The diagnostic lights flash in different sequences when I power up the tower, but this stops after about 5 seconds. After this the only light that goes on is the cylinder symbol, I think this is the light to indicate accessing the RAM?
Do you want to know the exact sequence of the diagnostic lights during boot up?