I've been out of the pc building for the last 5-10 years. My sons are getting into gaming so I figured I'd dust of my skills and build a new pc for them. I can't get the mobo to post, no bios, nada. No bios beeps but I think that might be old school. I've reseated the cpu, memory, removed everything not necessary. Tired 2 psu. I've bench tested so it's probably not a grounding issue. Fans, lights, disk drive, all turn on. Any ideas?