I'm using an Intel i7-12700K with DDR4-3600 memory on an MSI Z690 Tomahawk. The system has worked for about four years, but it now refuses to POST when both RAM sticks are installed and the motherboard's memory warning light comes on. One stick works in either A2 or B2, while the other stick only allows the PC to boot in B2. I've reseated the components and replaced the CPU, but the behavior hasn't changed. The issue started after a BIOS update that was needed for the replacement CPU, and I've also tried disabling XMP and reverting the BIOS with the original CPU. What should I check next?
3 Answers
Try booting with only the stick that works in B2, reset the BIOS, and manually set the RAM to a conservative speed such as 2133 or 2666 MT/s. Then test the other stick alone in A2. If the second module fails in A2 but works in B2, compare the results with another known-good kit. That will help separate a defective module from a failed A2 memory channel.
The simplest possibility is that one of the RAM sticks has failed. Test each stick by itself in the recommended A2 slot, using default BIOS settings with XMP disabled. If one stick won’t boot in A2 while the other does, that stick is probably defective. You can also test the pair in another compatible system if possible.
Because the behavior depends on the slot, don’t rule out a motherboard memory channel problem. Clear the CMOS completely, load BIOS defaults, and test one stick at a time in A2 and then B2. If both sticks work in B2 but neither works properly in A2, inspect the CPU socket carefully for bent pins and make sure the cooler isn’t applying uneven pressure. The memory controller is on the CPU, so socket contact can affect one channel.
A BIOS update can also reset or change memory training settings, but if the system still fails with XMP disabled and default speeds, I’d focus on the socket, motherboard, or a bad DIMM rather than the memory profile.
I’ve tested them individually, and the second stick only works in B2, so I’m not sure whether the stick or the channel is the problem.