Try to set the default settings on the BIOS. As the system is not showing any display, try this. Turn the system off, unplug the power cable, take the CMOS battery out for 5 minutes, and then put it back in the same position. That will clear the CMOS and set the defaults, then boot the BIOS and set the correct data and time. If you have any further problem, turn the system off, set the system with basic configuration (no hard drive, CD and one memory stick on the blue DIMM closer to the processor), then move the BIOS jumper one pin over, it will allow you to boot to the BIOS automatically, there set the defaults with F9 then save&exit with F10. After that you could add the rest of the part.
You can check the BIOS jumper position in the following link : Page 54
Try to check the memory voltage, this system supports memory with a voltage rating of 1.65V or less.