By booting and reading the RAM Memory Slot Tester, it can indicate the error in the motherboard circuit for further repairThe error can be detected by the LED light, indicating open circuit, short circuit, data line or address lineInstall the 3.3 v (CR2032) battery on the tester, motherboard does not need power on, on the tester's buttonIf the LEDs all light up and the brightness are all the same, the signal is there is no problemLight out or weak light signals gives problem. You must refer to sign indication in addition to that LED lightSize: 13.3 * 6 cm Material:PCBcolour:greenPackage Contents:1 * Tester cardOnly the above package content, other products are not included.Note: Light 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.