DRAM Debug Light After Installing a New PC in the Case

Because it worked before being installed in the case, test it again outside the case with only the essentials connected. If it works there, carefully check that the case has no extra motherboard standoff or screw touching the back of the board. If it still fails outside the case, test one memory stick at a time in the recommended slot, then try the other stick.

The memory modules don’t look fully seated. Make sure each stick is pressed firmly into the slot until the latches lock into position. Also, use the recommended slots from the motherboard manual—typically the second and fourth slots away from the CPU for two sticks.