One of my other computer's, when you push the power button, does not do anything.  It turns on, there is a fan running, and you can see that the power ligh is on and thats it.  No beeps from the bios or anything.  Also, my monitor doesnt detect a signal coming from the PC so it stays on stand-by.  I TRIED using the search but i couldnt find anything.  Any help on what this could even be would be great. ( and im no stranger to jarrgon either :-P).  

-RyanOne or more of the COMPONENTS INCLUDING the monitor has become unseated somehow.
Power down and remove the power source completely from both the monitor and the case.
Making sure you are properly grounded check all connections...biggest and usual suspects: RAM chips, video cards, and or IDE drive cables.
While you are in there do some general housekeeping getting rid of all dust bunnies etc.

Power up and let us know...

patio.  well, you got me

by unseated, do you mean something is loose and just needs a good unplugging and plugging back in?That's what he means.Sounds like the drive has died or the cables to the drive are loose.

How old is it and how old is the CMOS battery?i have 2 pc with this same problem.light and fan come on but thats all.the moitor says cable unplugged.i've tryed different video cards,hard drives,cables,MONITORS,even cpu.any ideasWhich country are you in Jimmy? Is the mains voltage set right is the first thing. How about the Power Supplies themselves?

Has either unit been affected by lightning or voltage surges/spikes?

Were both units using an UPS and protected against surge/strike? Quote

i have 2 pc with this same problem.light and fan come on but thats all.the moitor says cable unplugged.i've tryed different video cards,hard drives,cables,monitors,even cpu.any IDEAS