ok....just for giggles.
Take the motherboard out of the case and put it on the motherboard box or something, plug in your graphics card with the power plugged in as well, re-seat your ram and leave one stick in, plug in your psu 24 pin connector and 4 pin connector by the cpu.
Then try and turn it on...you'lll probably have to 'short' the power pin though on the motherboard...unless you can plug in the power switch from the case.