My Dell E521 has been on the fritz for about a year.  As soon as I turned her on she would go right into Entering Power SAVE and shut down.  I have DONE some research on Dells tech support and FORUM site. I am not a computer whiz, and can't tell if the computer is worth the investment of a new mother board.  From what I can tell from the Dell support forum site it sounds as if a new mother board might only be part of the solution!  Can anyone out there help me?   monitors turns into power SAVING mode if it don't get any signal from your CPU. Diagnosing your CPU box first is a good starting point.

check the power line.
power chord, power supply, then motherboard.

I hope that helps.I would at least try a different Power Supply before assuming it is the MBoard.Thank you so very MUCH for all your input!  I took my tower to a computer repair shop recommended by a friend.  He did check it over and it is a mother board problem (mother board is burnt up).  I want to get my tower fixed (it's cheaper then buying a new PC since I am out of work.)  Is there any other things I should have the repair man check before I take home my tower?      Ask him what parts he's replacing...
Ask him what the cost will be...

Other than that if you choose to do it yourself we will be here...Of course building it yourself brings you valuable memories and knowledge... and fun. It's not too hard either. I can get you great deals, that's for sure.