This 20+4 pin PSU power supply tester is a reliable tool for testing your PC's power supply. It is compatible with ATX, BTX, and ITX motherboard configurations, helping protect your system from potential damage. The unit supports multiple connectors, including 20- and 24-pin power supplies, SATA power, Pentium 4 power connectors, 6-pin PCI-Express power connectors, 8-pin CPU connectors, floppy drive connectors, and standard 4-pin power supply connectors. Equipped with four alert indicators, the tester detects low or high P.G. values, low voltage, overvoltage, and no voltage conditions. Its durable design ensures long-term use and is ideal for tech enthusiasts, hobbyists, professionals, and anyone needing a comprehensive power supply tester for their computer. The device features a backlit bright blue LCD display that shows real-time voltage readings and emits an audible beep when an issue is detected. This allows for quick and accurate diagnostics of your power supplys performance. Multiple rugged plastic ports support floppy, HDD, CD-ROM, SATA, 4-pin (P4), 6-pin (PCI-Express), and 8-pin (Dual-CPU) power connectors. A 20-pin or 24-pin connection is required to test other cables. Each tester comes in a sturdy plastic housing designed to protect internal components from impact and wear during transport and regular use. This versatile power supply tester works with most personal computers and can be used at home, in the office, or on-site. Note: If the tester emits a continuous beep and the 12V2 reading shows "LL," this does not indicate a fault in the tester or power supply. It means the second 12-volt rail is not detected, which may occur if you are testing a power supply that does not have a second 12V rail or if the rail is inactive.