This 20+4 pin PSU Power supply tester is a powerful tool for testing your PC's power supply. This tester is compatible with ATX, BTX, and ITX motherboard configurations and help you avoid expensive damage to your computer. This unit is capable of testing multiple connectors: both 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 alarms, this tester alert you of lower or higher . values, lower voltage, over voltage, and no voltage. Its robust design is made to last and is Perfect for tech enthusiasts, ambitious hobbyists, tradesmen, and anyone seeking an power supply unit tester for their personal computer. Featuring a backlit, LCD display, this power supply tester can verify that every part of your computer power supply is fully operational. It provide you with voltage read-outs and lets out a clearly audible beep if it encounters a problem with your power supply. ​Multiple, plastic ports can accommodate floppy, HDD, CDROM, SATA, 4-pin (P4), 6-pin (PCI-Express), and 8-pin (Dual-CPU) power supply connectors. You need to have 20-pin or 24-pin cable connected when testing any other cable. Each of these testers is specially designed with a plastic casing. It is reinforced to keep the internal electronics well-protected from dings and scratches that can be sustained during port and from regular use. The multi-use power supply tester can connect to most personal computers. Use it , the office or anywhere you have a computer. NOTE: If your power supply tester produces a constant beep and the 12V2 indicates "LL," this does not indicate that your power supply or the tester is defective. Instead, it means the 2nd 12-volt rail is not detected. This could be caused by two things: either you are testing a power supply that does not have a 2nd 12-volt rail or you h