Computer repair technicians take malfunctioning computer hardware and software, then perform the necessary steps to diagnose and ensure the systems are returned to a usable state. Technicians also build and assemble personal computers and servers, and may set up local area networks of computers and other related devices.

Technicians mainly deal with the hardware components of computer systems. Although they also deal with software, a technician may be called upon to install or replace drives, memory, and cards in computer systems. A computer technician may be required to build a system from components and load the operating system software on to the hard disk. The technician will then locate and install the necessary programs, called drivers, that allow the operating system software, such as Windows, to work with the hardware.

A computer repair technician will also work with the software of computers. This is usually the operating system software. Computers may get viruses or other malware infections and a computer repair technician may be called upon to remove the offending programs. If the operating system software doesn't function and cannot be repaired a technician will usually back up the users data, if possible, and format the hard disk with a new copy of the operating system.