My PC has been running for about two years, but it suddenly began crashing with BSODs before Windows could load. Windows eventually entered recovery mode, but startup repair and system restore both failed. Reseating the RAM and CPU did not help, and the system now will not boot even with one memory stick installed. The CPU fan does not spin, although the case fans do, and I cannot reach the BIOS.
The motherboard is an ASRock B450M. About a year ago it was replaced under warranty because it stopped detecting one RAM stick, would not reliably run in dual-channel mode, and even small bumps to the desk could freeze the computer. Around five months after the replacement, similar problems returned: the system would usually only work with one stick, and sometimes it failed to detect the other one entirely. Given this history, should I replace the motherboard, RAM, or CPU? The motherboard seems most suspicious, but I would like to confirm before buying parts.
3 Answers
The earlier Windows crashes could have been caused by unstable memory, but the current no-POST condition is a separate hardware-level problem. Clear CMOS, try a bare-minimum setup with one RAM stick, and disconnect drives and USB devices. If there is still no display or BIOS access, have a shop test the RAM and power supply in known-good hardware. If both memory sticks work elsewhere and the power supply is healthy, replacing the motherboard is the most reasonable next step.
The motherboard is the leading suspect given that two boards have shown the same memory-channel and slot symptoms. However, do not buy a replacement yet if you can avoid it. A faulty RAM stick, damaged CPU memory controller, bent socket pin, or power problem can also cause these failures. A repair shop or a friend with compatible hardware can test the sticks, board, CPU, and power supply much more reliably than guessing.
If the computer can reach the firmware screen, test each memory stick separately in every slot and run MemTest86 or MemTest86+. Since it no longer reaches BIOS, those tests are not possible right now. Check the motherboard’s diagnostic LEDs or beep codes, reseat the 24-pin and CPU power connectors, and inspect the CPU socket for bent pins. Also make sure the CPU fan is connected to the CPU_FAN header; some boards refuse to start when they do not detect a CPU fan.
The CPU fan does not spin, while the case fans do, and the machine never reaches BIOS. That makes checking power connections, the CPU_FAN header, and the socket especially important before condemning the RAM.
The slot I normally use has now stopped working too, so I cannot test the sticks properly. I may take the system to a repair shop or borrow a compatible PC for testing.