The Power Supply Unit (PSU) is the component responsible for converting AC power from the wall outlet to the DC power used by all other components in the computer. A complete failure of the PSU means no power is delivered to the motherboard, CPU, or any other part of the system. This results in a "dead" computer with no signs of activity, such as lights, fan spin, or sounds, which directly corresponds to the user's report that the PC "does not turn on." Therefore, a faulty PSU is the most probable cause of this specific issue.

B. GPU: A failed Graphics Processing Unit (GPU) would cause a "no display" issue, but the computer would still power on, with fans spinning and lights illuminating.

C. RAM: Faulty or improperly seated RAM typically leads to a Power-On Self-Test (POST) failure. The PC would turn on but fail to boot, often signaling the error with beep codes.

D. CPU: A failed Central Processing Unit (CPU) is a critical failure that prevents the system from booting (no POST), but it would not prevent the PSU from supplying power to the motherboard and fans.

---

1. Vendor Documentation: Dell Inc. (2024). How to Troubleshoot a No Power Issue on your Dell Desktop or All-in-One. Dell Knowledge Base

Article 000124349. This guide identifies symptoms of a no-power issue as "no signs of power

" "no LED lights

" and "no fan noise

" and lists troubleshooting the PSU as a primary step.

2. Vendor Documentation: Intel Corporation. (2020). Troubleshooting No Boot Issues for Intel® Desktop Boards. Support Article 000056353. This document distinguishes between "No Power" and "No Boot" scenarios

explicitly stating for "No Power" to "Verify the power supply is operational."

3. Academic Publication: Schroeder

B.

& Gibson

G. A. (2007). A large-scale study of failures in high-performance computing systems. IEEE Transactions on Dependable and Secure Computing

4(4)

337-346. In their analysis of hardware failures (Table 2

p. 341)

power-related issues (including power supplies) are identified as a significant cause of system outages

reinforcing the PSU as a common point of failure. DOI: https://doi.org/10.1109/TDSC.2007.70229

4. University Courseware: Patterson

D. A.

& Hennessy

J. L. (2017). Computer Organization and Design RISC-V Edition: The Hardware Software Interface. As used in courses like University of California

Berkeley's CS61C. Chapter 1

Section 1.4

"Under the Covers

" describes the function of the power supply as the component that provides electricity to the processor and other components

establishing its foundational role in powering the system. A failure here logically precedes the function of all other listed components.