I recently re-assembled my computer which was taken apart. The only thing that was different is the Harddrive was formatted when connected to another comp. Now i get nothing. No display, no nothing.  PLEASE HELP!!!Trev:

Does the Power On Self Test (POST) end with any beep tones?  

Regards,
Doc

First of all, make sure that all connections are tight. Secondly RAM sticks are connected firmly and in a correct sequnce and there is no dust between RAM sticks and RAM slots.Now turn your PC ON. If it works then fine otherwise restart and press numlock number of times. If numlock light doesn't turn ON there MUST be RAM problem.
Before doing all above, make sure that your monitor's data cable is working properly.
Dr WahabCheck your jumper connections..such as power switch plug is hooked up on the right jumper..etc.  I recently had the same problem with a new case...my power supply was too powerful for the ATX to support it.  But when I reconnected my hardware back in its orgional case I had to reconnect the jumpers...if they are not on the right jumpers your computer will not power on...because newer power supplies require the power switch, unless it says otherwise in its documentation.You could have PROBLEMS, becuase no power is getting to switch, or telling the power supply it is on...something like that...Any  check your ram, check your cables, but check to see if you may need a new power supply, but first check your jumper connections on your motherboard. Quote

my power supply was too powerful for the atx to support it.