The 1155 LED tester is used to test for open and short circuits in the bus signals connecting the CPU socket and the Northbridge on the motherboard. It uses LED indicators to replace the traditional method of manual measurement with a multimeter, preventing damage to the CPU during repair or debugging. It is an essential tool for repairing and debugging computer motherboards. Only Supports testing LGA1155 CPU Socket. When the 1155 test LED is placed in the CPU socket and the CPU socket cover is pressed down (note that the motherboard should not be powered on), the DMI, FDI, synchronization, and clock signal indicator lights on the test LED will all light up. These signals are connected to the Northbridge chipset. If any light does not light up, it indicates an open or short circuit fault in that signal. The CPU lever can be moved to further pinpoint the fault location using a multimeter. Precautions: The motherboard must not be powered on during testing. After multiple uses, the test LED brightness may decrease because the battery voltage is insufficient. Please replace the battery yourself. Due to differences in motherboard design and chipset among manufacturers, some signals displayed by this tester may vary. Please have troubleshooting and repair personnel use the same motherboard to compare and diagnose the fault. Color: Black Material: PCB Package Contents: 1 * CPU Socket Tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.