I have a list of no-POST/no-run causes and you can find the full list
here if you want to see it

but here's a few random tries:
1) Ultra-brand power supplies... I know there's some guys around here who say they're no worse than average, but there's also guys around here who'll tell you that theirs went *POOF*.
All that glitters is not gold... Not easy to test without dishing out another $90-ish for a known quality-brand unit, though (Fortron Blue Storm comes to mind)
2) Do you definitely have all the motherboard's power cables hooked up. 24-pin main, 4-pin ATX12V secondary, and I don't know yet if your board uses a drive plug as a tertiary or not, but your manual would show the power fittings, Intel's good about the documentation.
3) New builders, which you might or might not be, sometimes forget important little things like putting standoffs under the motherboard :Q
standoffs
4) Try taking out the PCI cards, maybe they're causing an IRQ clash at the chipset level.
5) If it isn't getting anywhere, taking the board out of the case, laying it on cardboard, and benchtesting it with just the bare essentials for POST (power supply, video card, CPU/heatsink, memory, NO drives, NO keyboard/mouse, NO case ports) may help narrow down what to be suspicious of.
6) If a PS/2 (round-plug) keyboard happens to be in the mouse port, that'll stop some boards from POSTing right there, check if you're not sure... purple for KB, green for mouse
Hope the answer's in there somewhere, or otherwise there's that list I made
