Why does my AM5 PC double-boot after a BIOS update?
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MellowPine42
Since updating my BIOS, my PC shuts down once and then boots normally whenever it starts from a completely cold state. It powers on, runs for about 5–10 seconds, shuts off for 3–5 seconds, and then starts again and loads Windows without any errors. This does not happen during restarts, and leaving the power strip switched on also prevents it.
The behavior began only after the BIOS update. The system is stable once Windows starts, and there are no related event viewer errors. EXPO I is enabled for my 64 GB DDR5-6000 kit, as it was before the update. Could this be normal AM5 memory training, or does it suggest a hardware or BIOS problem?
System: Windows 11 Pro, Ryzen 9 7950X3D, Crosshair X670E Hero with BIOS 3902, 64 GB Corsair Dominator Titanium DDR5-6000, RX 7900 XTX, Seasonic Prime TX-1000, and an H170i LCD cooler. BIOS settings are otherwise mostly default, with UEFI mode and standard Secure Boot enabled.
Answers
Try temporarily disabling EXPO and see whether the double boot disappears. If it does, the behavior is likely related to memory training or EXPO stability rather than Windows or the graphics card. You can then decide whether to leave EXPO off or adjust the memory-training settings.
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On the Crosshair X670E Hero, enabling Memory Context Restore may prevent the board from retraining memory on every cold boot by reusing the stored settings. Some systems behave better with Power Down Enable disabled when Memory Context Restore is enabled, so test the options one at a time and reset them if stability worsens. The fact that keeping the power strip on avoids the issue also points toward a full memory-training cycle rather than a Windows problem.
MellowPine42: When the power strip stays on and I shut down only Windows, it boots normally without the extra power cycle.
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This pattern is consistent with DDR5 memory training on AM5. A BIOS update can clear the previously trained memory values, so the first cold boot may attempt training, shut down, and then boot successfully with the new timings. Restarts usually avoid it because the memory has not fully lost power. With 64 GB running EXPO, training can be more noticeable. It is generally not a sign of a failing component if the system is stable afterward.
MellowPine42: That makes sense, but it happens on every cold boot rather than only the first one after the update. Is repeated training still expected?
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MellowPine42: I have not tested with EXPO disabled yet, but that will be my next check.