Not really needed to pull it out but it is better to place the power supply near the motherboard in order to have a room for the connection. Detach all wires terminals from the motherboard and put a mark on them so you can easily return them again later. Remember, place the motherboard on the non-conductive materials in order to prevent it from short. Connect the wires from the power supply to the 20 pin and 4 pin sockets of the motherboard. Be sure the monitor is attached to the vga socket.
1. Did you turn it on through the motherboard terminal? It's wires from the power switch button on the front panel of your pc case to the motherboard. So that you can determine if the power switch is sticky or broken.
2. Did you clean the contact of the memory stick before inserting it to the dimm socket? Use a pencil eraser to clean the contact and reseating it to the socket several times. Use one stick at this time then restart your pc.
3. What video card do you use? Is it integrated to the motherboard or pci video card? If pci card, clean its contact with a pencil eraser several times then insert it to the slot. Then restart your pc.
Check if it will boot.
Please specify your new motherboard make and model..