A) You weren't FOLLOWING Anti-Static Precautions, and Static shocked your hardware components inside.
(See the little Processor ghost?
OK, OK. JUST KIDDING AROUND!
Get's pretty lonely here in the FixYa halls. Did see an Armadillo going down the hall, though. NO! For real!...........crickets chirping)
B) You don't have the main Front Panel wires, connected correctly to the pins of the Front Panel header, on the motherboard.
We'll go through them together.
C) The Power On switch is cr@P. (Did I say that out loud?)
D) The Power Supply is bad. Weak voltage power rail.
(Got a multimeter? I'll guide you in using it.
About $5 to $12, and located everywhere. Just a cheapee Analog multimeter will do)
E) The motherboard is mounted to a Support Plate. The Support Plate can be a separate metal plate; or is part of the computer case.
Mounting of the motherboard to Support Plate, is done with plastic Spacers; or metal Standoff's.
Metal Standoff = Brass hex shaped, and with a threaded end on one side, and a threaded hole on the other.
IF, a metal Standoff is NOT matched up to a motherboard mounting hole, it can touch the exposed solder joints on the bottom of the motherboard; and short the motherboard out.
USUALLY, if the 'offending' Standoff is removed, the motherboard will work OK.
General rule of thumb is;
Motherboard mounting hole has metal ring - NO fiber washers. That's how the motherboard get's it's Ground.
Motherboard mounting hole has no metal ring? Use fiber washers.
At any rate, what is the motherboard manufacturer name, and model number;
what is the computer manufacturer, and model number.
Model number is on the back of the computer next to the Windows product key; or up on the side of the computer tower.
Post back in a Comment.
(Hurry, or I might go out with sum girlz)http://www.directron.com/atxswitch.html
[ Need to test the three main voltages coming out of the Power Supply.
3.3 Volts, (Orange wires), 5 Volts, (Red wires), and 12 Volts, (Yellow wires) All are DC Voltage.
ALL -> Black wires are Ground wires.
In comparison two D cell flashlight batteries produce 3 Volts DC.http://en.wikipedia.org/wiki/Computer_power_supply#Wiring_diagramshttp://www.playtool.com/pages/psuconnectors/connectors.html
(I mean joecoolvette)