Make sure you ground yourself. I recommend this band to make the process easier.
Ensure that you are working on a non-clothed surface (carpet, rug, clothing), and are working on a hard surface such as a turntable, desk, or hardwood/tile flooring.
Remove all parts from their packages:
Remove heatsink and CPU from box.
If you are using a third-party heatsink, make sure that you check out this How-To on how to apply thermal paste.
Open the motherboard latch on for the CPU socket.
Open the cover plate.
Gently place the CPU in the socket and give it a slight wiggle to ensure it is installed safely.
WARNING: Ensure that the CPU indents fit into the socket. This step should require little to no force.
Close the CPU cover plate. The plastic cover should pop off by itself.
WARNING: DO NOT TOUCH THE SOCKET PINS.
Install the RAM
WARNING: To ensure that the RAM is oriented correctly, check for a notch in your RAM stick and slot. The two should line up so that your RAM stick and slot will not get damaged by additional pins in the incorrect place.
Push the RAM slot locks back. They are located on the side of the RAM slot.
Insert the RAM stick into the slot and push on the sides of the RAM stick until the lock pops back up by itself.
Place the Motherboard into the Case.
Look at the case manual to check the screw mounting positions, and screw the Motherboard into place in the case.
Install the Graphics Card.
Remove 1, 2, or 3 brackets from the side of the case to fit your graphics card.
Gently Pop the Graphics Card into the PCIE slot.
Screw the screws back into the PCIE slot cover holes once the Graphics Card is installed to help keep it in position.
If using SLI or Crossfire, do the same process multiple times and attach the Crossfire or SLI bridge to the graphics cards.
Install the Power Supply.
Align the Power Supply to the screw mounting holes, and screw the Power Supply in tightly.
Refer to the Motherboard and Power Supply Manual to connect the correct ports.
Also connect the case cables to the motherboard.
Close the case.
Your desktop is now assembled!