Sounds like a bios problem to me. But before we go into that, remove all non essential hardware. Put in a video card, and only the hard drive you instend to install to. MAKE SURE the hard drive cables are properly installed. The computer will not boot if the cable is reversed. If you are not sure, reverse the cable from the way it currently is. If the computer boots, you found your problem.
Now, assuming that isn't your problem, back to Bios. Look in your motherboard manual for the CMOS Discharge jumper. On your board, it should be located just below and between the battery and the South Bridge.
Turn off your computer. There will be 3 pins. The jumper will be on pins 1 and 2. Pull it off and stick it on pins 2 and 3. Wait about 5 seconds. Then, take it off and put it back on pins 1 and 2. This will reset your Bios to factory defaults. If this DOESN'T work, then you know it's not your Bios.
Then, check the CPU. Make sure it is seated properly. Also, make sure the heat sink is seated correctly on top of the processor. While you are checking this, it might be a good idea to apply a thin layer of thermal grease to keep things a little cooler. The CPU should fall into the socket. There should be NO NEED FOR FORCE. If you have to push it down, then it's not in there correctly. When I got my KT7-Raid, the processor was not completly into the socket. The KT7 boards have a little heat diode under the processor, that stops it from falling in all the way. Bend it down, until it is about 2 to 3 milimeters above the edge of the socket. Then, place your processor into the socket. Lightly press on the four sides, one at a time. If the processor pivots freely, (ie, all the pins fit the holes properly) gently push it down, further bending the heat sensor, but insuring a good contact between the sensor and the processor.
BE VARY CAREFUL when re-installing the heat sink. You should make sure it is as level as possible over the processor before you apply force to lock it down. My global win FOP32 took a LOT of force to get in. If you rest the heat sink improperly, you risk destroying your CPU.
Next, check your memory. Ensure the modules are seated correctly. They should be firmly seated in the slot, perpendicular to the board. If one end is a little higher than the other, or they are not firmly seated, remove them, and re-instert them into the slots. If you have one module, ensure it is in Bank 0/1. If you have 2, Bank 0/1 and Bank 2/3. If three, all banks will have one of course.
NOTE: Be sure to ground yourself on a metal portion of your case before handling memory. Static electricty can quickly destroy your memory module.
Now, as I said in the beginning, you should have removed all non essential hardware. There should only be installed one video card, and one hard disk, keyboard, mouse, and monitor. Try your boot again. With a clean BIOS, correctly installed processor, and properly seated memory, if it still doesn't work, I would begin looking at bad hardware.
Hope this helps.