Remove everything except the CPU and CPU cooler... Everything, the cd rom the power the HDD... Everything
Plug in the motherboard power
Add only one stick of RAM
Connect your monitor to the VGA connection
Look for CMOS or BIOS reset, press this or short it using a flat screwdriver
See if it turns on, if it does add one component at a time until it stops
If it doesn't then try second stick of ram