New build on a 5 year old mobo? I'm going to assume this motherboard was purchased used. The best way to troubleshoot a motherboard is by "breadboarding" it. Disconnect everything from the motherboard, leaving only ram and CPU/heatsink and speaker connected. Add both power connectors, turn on power supply. Arc the two power pins on the motherboard (usually labelled pwr_+/pwr_-). See if your CPU fan comes on and you get a "good POST" signal of one beep (may take up to 30 seconds for the beep). You can keep your monitor plugged in for this - there should be an accompanying screen saying no OS found.