Decide on what type of recording software you want to use. Popular options include Pro Tools, SONAR, Cubase, Ableton Live, and Nuendo.
Choose a sound card that will meet your recording needs, based on the number of inputs, or tracks, you want to record at once; some sound cards are specific to certain recording programs, such as Pro Tools.
Decide whether to use a dual monitor setup or not. Some engineers like to have two monitors, one with the software mixing console and the other with the main recording effects and mixdown displayed.
Choose a motherboard that supports a lot of RAM, preferably 6 GB or more. The more RAM you have, the more stable the recording program and the more effects you can run at once without the system crashing.
Screw the motherboard into the case.
Install the processor and processor fan in the slot for them on the motherboard.
Install the RAM into the RAM slots.
Screw the hard drive and DVD-R drive into the slots in the computer case.
Connect the power supply to the motherboard and hard drive.
Install the video card and connect the display monitor(s) to the card. Install the sound card.
Boot the computer and install the operating system.
Install the recording software and configure it to recognize your sound card.
Connect the studio monitors to the sound card. Also connect whatever mixing console you have to the card, if the external card doesn't have a mixing console built in.
Connect an external hard drive to a USB slot and use it for backing up recordings.