no boot

need help with a new build.
Asrock939 dual sata2, amd 3500 64 bit, 512 mb 400 DDR, ATI Radeon 9700 128 mb,Maxtor 250gb hd, pioneer dvd/cd.
memory and hard drive work fine in old system. OS Windows XP Pro.
when assembled on new asrock m/b and powered on - the leds light up, the fans power up, the hd whirrs for a couple of seconds - then nothing.
tried changing slots for mem, cleared cmos, checked seating of mem and graphics card umpteen times.
Will not get to POST or boot.
M/board, processor amd memory are brand new.
finding it very frustrating, please can anyone help.

what psu are you using..... have you got the 4 pin connector pluged in to the motherboard?

Curly

Hi
350 watts PSU, but I did purchase a 450 watt PSU and tried that. No luck
Yes I do have the 4 pin connector plugged in.

So which model is your Asrock mobo and which core is your 3500+ do you know?