1 pcs DDR2 and DDR3 Illuminated Tester & 1 pcs DDR4 Test Card Motherboard Tester By booting and reading the RAM Memory Slot Tester, it can indicate the error in the motherboard circuit for further repair The error can be detected by the LED light, indicating open circuit, short circuit, data line or address line Install the 3.3 v (CR2032) battery on the tester, motherboard does not need power on, on the tester's button If the LEDs all light up and the brightness are all the same, the signal is there is no problem.Light out or weak light signals gives problem. You must refer to sign indication in addition to that LED light DDR4 testing CARDS fully the , for AMD all DDR4 interface board, use leds to indicate that the data line address line open circuit and short circuit. Used to repair is not switched on, does not display, does not read failure such as motherboard, memory is an essential instrument for repair computer motherboard Equipped with battery (CR2032, 3V) insert battery to insert the test card and insert into the corresponding type of motherboard, and insert the CPU motherboard, presses the switch button, test card can assess motherboard memory part of open circuit. Short circuit fault If a lamp is not clear, Could memory and CPU holder or with short circuit, memory slot is If a light, clear, must check the signal and power supply circuit Size: 13.3x 6 cm Material:PCB colour:green Package Contents: 2 * Test Card Only 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.