Help - won't POST, just shuts down automatically

[metroplex]

I have a PC that won't POST but will shut down during startup after about 3 seconds. There are 3 LEDs on the mobo, an amber that signifies +5V, a green that signifies its powered on, and a red.

Right before it shuts down, the red LED goes on.

I cannot keep the system powered on unless I hold down the reset button.

All the fans and drives power on but everything shuts down afterwards.

I have tested it with a known-to-work power supply and another known-to-work PSU.

Any ideas?

mobo: Abit KX7-333, Ram: Crucial PC2100 DDR x 2 sticks, 2 HD's, 2 optical drives, GeForce FX 5600

 

[deathwalker]

Is this a problem that came on suddenly ...or is it an initial build problem? If this is an initial build problem it almost sounds like you may have gotten your front panel wiring bundle connected improperly to the mobo..more specifically perhaps your power on or reset cables connected to the wrong pins.

 

[mechBgon]

I think that if you look up the red LED in your owner's manual, you'll see it's the CPU-overheat indicator. Check your heatsink installation against the third and fourth photos here.

 

[metroplex]

You guys are the BEST!

It happened all of a sudden and I couldn't figure out why until MechBgon said something about the CPU overheating... I had set it to shut off the PC upon the CPUFAN failure... for some reason the CPU fan always reads 0 RPM until after awhile when the system boots up. Thus it would never boot up... I reset the CMOS and set it to shut off the PC only when the CPU temp reaches 65 *C and ignore the fan speed. I'm sure during normal use if the CPU fan failed, the temp would hit 65 *C fairly quickly.

Again, thanks for the fast responses!!