Wont Boot...HELP QUICk

reseat everything... video card, memory, NIC and anything else that plugs into the board.

Power it up. Does it beep?

The important thing is the beep. If it does not, remove the memory.. Does it beep? If it does, try that memory in a different slot or try a different set of memory.

Need more info here,like:

How far does it get when you power on.. beep, ramcount, etc, and are there any error codes or beeps.if it doesnt get that far you need to check all connections maybe a loose one somewhere.

Make sure that you properly connect the right power cord as prescribed by your power supply. You might have interchanged 100v to 220v.

Sayonara

Sounds like it may be the thermal sensor on the motherboard has failed.
When the fans go off, the power supply is shutting down, and it is not the overload sensor in the power supply, because when that trips, the light on the motherboard should go out.
That also eliminates shutdowns caused by shorts. (Loose screws, etc.)
Something is telling the power supply to shut down.
The CPU thermal sensor is the most likely, but it can also be the fan speed sensor, or other safety feature.
The last possibility, and least likely, is that the BIOS settings have become corrupt.
The BIOS is reset to the factory defaults by removing the battery.
Regards, Chris

The light on the mother board stays on as long as the power switch on the power supply is on. The button on the front of the computer that is connected to the 2 pins on the motherboard is what actually starts the system. Check the placement of the connector for the front power switch. If you remove the connector and touch the 2 pins with a screwdriver the system should start.

First, make sure the video card hasn't sliped up out of the AGP slot and that the memory hasn't popped out. Sometimes the memory takes quite a bit of force to snap in all the way and will pop back out.

Reset the CMOS. Follow the instructions in the manual to do so.

Go back through the assembly process and make sure everything is correct. Reseat the CPU and everything else. Try only installing the video card and ram then turn it on. If it comes up start adding components one at a time. More than likely in your excitement to get the new system up and running you just didn't get something connected all the way.