Check that the green led on your mobo comes on. If not, you have no power getting to the board. The best thing to do is stop for a calm down, then take everything apart and start over. Check the pins on the cpu, to make sure none are bent. Set the mobo on a cutting board (wood or plastic, no metal )and put the case beside it. Make sure that the switch on the back of the case/psu is off. Put the cpu into the mobo. Make sure it is going on the right way round, then attach the heatsink/fan. Make sure the memory will go right way around, then put that in. Put the video card in the agp slot, and make sure it is seated, with the bottom of the attachment plate sticking out past the cutting board. Look in the manual and make absolutely certain you know what pins the power switch goes to. Put a jumper accross these. Attach the power cable to the mobo. .attach the keyboard to it's port. Attach the monitor to your video card. Make sure the mobo is not touching any thing metal. When you turn the switch on the back of the case to the on position, you will have a few seconds to remove the jumper on the power switch pins, so be ready. Turn the switch on the back of the case to the on position, and first note if the led is turning on. If the led is turning on, pull the jumper off, and hopefully use the keyboard to get to bios. Your computer has started, so use the switch at the back of the case to turn it off again. If this has worked, take off the video card, and put it all into the case, and put the video card bak on. Try it. If it works, add one piece at a time, and check to make sure it works, after each piece. Good luck.