Bestec ATX100‑5 (P/N 5184‑2191) is a 100 W ATX‑form factor desktop power module used in HP/Compaq workstations and other computer systems, featuring a 20‑pin motherboard connector, multiple 4‑pin Molex outputs, an EPS 12 V connector, and a floppy drive plug. Common failure modes for this class include capacitor degradation on the +12 V rail, fan motor burnout, and voltage regulator dropout due to aging electrolytics or thermal cycling. Initial checks should verify that the PSU receives proper 120 VAC input, confirm all output voltages (+3.3 V, +5 V, +12 V) are within ±5 % of spec with a multimeter, and inspect for bulging or leaking capacitors and fan operation; if any anomalies persist, proceed to internal component testing or replacement.[oss-gpt-20b]