pc woul not boot up

I have a motherboard av49vn Shuttle AV49VN VIA Socket 478 ATX Motherboard / AGP 8X/4X / Audio / 10/100Mbps Ethernet LAN / USB 2.0, and intel proccessor Intel? Pentium? 4 2.6Ghz / 512K Cache / 400MHz FSB / Socket 478 / Processor
brand new antec power supply 1 gig memory, the connetions are all ok, but computer would not bootup, no fan to the power supply. pl. help.