Inspiron 545 Won't turn, no usb keyboard or mouse, monitor not working

Have a Dell Inspiron 545 tower that quit while I was using it.  Mouse and keyboard didn't work while Windows was running.  So I did a hard reset and now the computer won't turn on.

No light from the usb mouse, no keyboard lights (usb), no monitor but green light behind power supply.  Power light white and steady.  I have three fans running, one in the power supply, one on cpu and exterior fan.  I opened the unit and checked power to the hard drives either 5.0v or 12.0v and ground ok.

I followed one of the posts in this forum but didn't want to hijack it.  I followed the following procedure by Bev.  But after jumping the green and black wires and reconnecting, my computer runs now.  What does this mean, Need new power supply???

" First tturn off the desktop, remove power cord and hold power button in for about three minutes, reconnect power cord and power system on and see if this makes a difference.

No difference, try the following, if you are comfortable working around computers:

Note: The only 100% method of testing a PSU, is to install a known working power supply.

Unplug the cord from the power supply, hold the power button in for about 15/20 seconds, open the case, unplug the 24-pin power connector from the motherboard and jump the Green wire to one of the Black wires, reconnect the power cord and power the system, if power supply and case fans and the hard drive run, then the PSU should be good.

Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper.

Power supply checks out, again disconnect the power cord, hold the power button in for several seconds to discharge the residue power, reconnect the 24-pin connector to the motherboard.

Remove all PCI cards from the system, take out the video card [if applicable], disconnect all peripherals, except the monitor, mouse and keyboard and disconnect the power & data cables from all drives. 

Reconnect the power cord and power system on, see if you get a different LED indication on the power button, or 'Beeps'.

No difference, remove the memory from the system and try again.

Still shows no signs of life then you are looking at a motherboard replacement & maybe a processor. 

Bev."