Build a PC

Building a desktop

Building your own desktop allows for greater customisation and control. It's worth it even though it's harder.

Use standoffs under the motherboard mounting holes!
Read the manual that came with your motherboard.
Plug in all the power connectors.
If you have a graphics card, connect your monitor to your graphics card and NOT to the motherboard
Spread thermal paste however you feel like, use about half a pea size amount, if using the stock heatsink don't touch the preapplied stuff
Install the CPU heatsink before putting the motherboard into the case, unless it's a water cooling setup.
The CPU socket lever on Intel motherboards will be hard to push down and feel like it's taking too much force. That's normal.

4-pin molex	6-pin PCI-E	6+2-pin PCI-E	20+4-pin ATX	4+4-pin ATX12V/EPS	15-pin SATA	4-pin floppy

Commonly used for fans and older drives.	Used for graphics cards. According to the ATX specification, it should not transmit more than 75W.	Also used for graphics cards, but can (should) output up to 150W.	Used as the motherboard's main power source. Always plug in both parts.	Used as the motherboard's secondary power source, but still required for the motherboard to work. When using 8 pins, it's called the EPS connector, but if only using 4 pins, it's ATX12V.	The Serial ATA power connector is used for hard drives, SSDs and optical drives.	An obsolete connector, used for powering floppy drives.

PCPartPicker - Computer component aggregator and comparison tool dedicated to picking out compatible computer components, allowing one to seamlessly create a desktop.

Logical Increments - Formerly known as the "Falcon Guide", a good starting point to building a computer on a budget, components are grouped by price point.

ChooseMyPC.net - Cookie cutter PC build generator, also hosts several guides and resources related to builds.