Put monitor connector in the onboard video port and see if it will boot. If not, try removing the video card and see if that changes anything. (1 thing at a time). Try RAM 1 stick at a time, in all slots if necessary, then the next one. Is the CPU fan running? It should run full speed when trying to boot. If you get the same result of lights and fan immediately shutting down, I'd suspect the PSU. I hear that's a good PSU but if you have ruled out other components it's either that or the MB.