Hey,
I just got a new computer. the power supply humms on and the fan rotates tho the computer doesn not start ? hmmm... Ps. i have a 350Watt ... hope u can help me
Do the little LED lights come on from the front of the case or on your motherboard, if you have LEDs there? Any beeping sounds? Memory seated correctly? Same with graphics card?
Make sure all the connections are correct and tight. Sometimes one loose connection can make everything not work. It sounds like it might be the power connection from your power supply to your motherboard. Start there when checking everything out.