Usually you'll get some sort of beep code when theres a problem with your hardware IE:ram not seated properly,video card/pci cards not seated properly in the slots,ect.
Make sure your heatsink is on right and not backwards,my pc was doing the same thing but it would turn off a few seconds after I turned it on...That was due to my heatsink being installed backwards...
No beep code dosent exactally mean something is wrong with your mobo (it could be shot but thats not always the case)like I said) my PC would stay on for a few seconds and then shut down,no signal to the monitor and no beep codes...
Your best bet is to install one thing at a time, take every thing apart and start with the basic stuff needed (RAM, CPU, heatsink and mabe a video card if needed)...
Try putting your CPU and heatsink in and then fire the mobo up with out any ram in it,if you get some sort of beep code then the mobo is telling you theres a memory problem,you could even fire it up with no processor and it should alert you in some way that there is no CPU in the board...If this works then I'd rule out you having a bad mobo,but thats not 100% sure...
Just do one thing at a time,install the basic stuff needed then install one peice of hardware at a time that way you know what you did last and it's causing a problem...
