My PC ran normally for almost a year with one 16 GB RAM stick and one 8 GB stick, but then it crashed twice. I removed the 8 GB module, and since then the computer only boots intermittently. When it fails, the CPU debug light on the motherboard stays lit. Sometimes it eventually starts, but I'm afraid to shut it down or use sleep mode because the next boot may fail.
I've tried moving the RAM between slots, testing the 8 GB stick, removing the CMOS battery, reconnecting all cables, and—unsuccessfully—asking, begging, and lightly smacking the machine.
The system has a Ryzen 7 5700X3D, MSI B550M Pro-VDH WiFi motherboard, RTX 3060, Kingston HyperX 16 GB 2400 MHz RAM, EVGA 600W power supply, and several SATA and NVMe drives. What should I check to determine whether the RAM, motherboard, storage, power supply, or CPU is causing the intermittent boot problem?
3 Answers
The 2400 MHz single-stick memory is far from ideal for a 5700X3D, and mixing different capacities can sometimes make memory training less reliable. It may not be the direct cause, but testing with a matched 2-stick kit—ideally 3200 MHz or faster—would be worthwhile when possible. For now, test one module at a time in the motherboard’s recommended slot and leave memory overclocking or XMP/DOCP disabled.
Since the problem is intermittent, isolate the hardware instead of repeatedly trying random changes. Clear CMOS properly, use only the CPU, cooler, graphics card, and one RAM stick, and disconnect the extra drives and USB devices. If it still randomly stops at the CPU debug light, inspect the CPU power connector, reseat the CPU and cooler if necessary, and test with another known-good power supply or memory kit. Record which debug LED stays on each time, because a CPU light can sometimes be triggered by a memory-training or power problem rather than a failed CPU.
More details about the failure would help narrow this down. What exactly happened during the crashes: a blue screen, an immediate power loss, or a freeze? When it fails to boot, does the system reach the BIOS, show a black screen, or simply stop with the CPU debug LED lit? Also identify the exact 8 GB module and confirm that both sticks were tested individually in the recommended slot.
It’s also worth disconnecting every storage drive except the one containing Windows. A failing SATA or NVMe drive could cause crashes or prevent Windows from loading, although it normally would not explain a CPU debug light during POST.