My desktop dell dimension E521 won't come on. The power button just blinks green. A new power supply was tried but that did not work. What is it likely to be and is it gonna be worth fixing?

Maybe a bad PSU? You said you looked at every site, but look at these: http://support.dell.com/support/edocs/systems/dimE521/en/SM_EN/adtshoot.htm#wp1054146 OR : http://en.community.dell.com/support-forums/desktop/f/3514/t/19341603.aspx

A solid green light means the computer is operating normally.

A solid yellow light indicates the power supply is operating normally but the computer is not processing data.

This could mean there is a problem with the CPu or another component on the motherboard.

((A blinking yellow light indicates the power supply is receiving power from the wall, but not functioning properly.
This generally means the power supply itself is bad and should be tested or replaced.))

A blinking green light means the computer is in standby mode.

You should consider visiting Dell Support and downloading the manual for your

your Dell computer. So use the LED power light codes if your Dell computer has them.

hope this helps

An Amber blinking power button indicates a low voltage problem. This can be caused by a defective power supply or a defective motherboard. Since you replaced the power supply, my guess is that the motherboard has a problem.
Just to make sure that nothing else is causing the problem, remove any PCI cards like modem, video card, sound card, etc... Remove the memory modules and disconnect cables to CD/DVD drives. Look at the USB ports to see if any are damaged.

A Blinking Amber or Yellow power button means that the power supply is receiving power from the source but is unable to properly distribute it to the components. This can be caused by a defective power supply or a defective motherboard. Just to make sure that nothing else is causing the problem, remove any PCI cards like modem, video card, sound card, etc... Remove the memory modules and disconnect cables to CD/DVD drives. Look at the USB ports to see if any are damaged.

Try Hitting the Power Button. Some systems require you to hit the power button to bring it out of Power Save, Sleep or Hibernation.

If its a desktop unit have someone open and examine the power supply for puffed up caps---if this problem usually it will begin where have to try to turn it on a few times and then it gets worse.

if puffed up caps you have two choices---replace all the ones that have this issue or buy a generic power supply to install in the tower.

see typical caps--if not perfectly flat or showing any brown material coming out of top or bottom they are bad.
note the two here with tops puffed up.

Firstly check the power supply and all the cable are properly are plugged or not.
After check The SMPS FAN are working or not or cpu fan is working or not .
put out the ram and properly make it dust free. and after put is properly.

Blinking Green power button indicates the computer is in a Windows® Standby power-saving state. Do any LED error codes display on the front? They are located next to the 2 USB ports on front.

Flashing green power light indicates that the computer is in a Windows Standby power-saving state.

hi !
If your have already changed the power supply, there is still a lot of main points of failure in the no power situation. If the motherboard has a flea light, then it could be one of the components. It can be the memory(if no beeps are heard, then memory is not the cause), it can be the processor, or it can be the control panel, in which the power button is attached. Try to check the cables as well.
Cheers !