Troubleshooting PC startup issues: checking debug lights for hints
Troubleshooting PC startup issues: checking debug lights for hints
My Issue Summary: My computer sometimes fails to start up (no POST) – only occasionally. When it does, everything works perfectly. This unpredictability makes me puzzled about the cause. I’ve shared this problem before but haven’t gotten any responses. I followed all the troubleshooting steps from the README, yet nothing fully resolved the issue. I’m trying to note some possible reasons so others might assist. Any guidance would be greatly valued.
My PC Details:
- CPU: AMD Ryzen 3600
- Motherboard: AsRock B550M Pro4
- GPU: XFX Radeon RX 7700-XT
- Power Supply: Enermax Revolution D.F.12 850W (80+ Gold)
- RAM: Klevv 16GB, dual channel, 3600MHz
- Storage: NVMe M.2 256GB (Windows only), WDC SSD 1TB (game), WD Blue HDD (data)
The Problem: My PC occasionally doesn’t power on at all (no POST), but usually boots fine. This inconsistency is confusing. I checked previous No POST guides in the README, but none solved the matter. After updating my BIOS to 3.40, incidents dropped compared to 3.61 which caused more failures. Initially, I suspected the BIOS version was the culprit. Recently it started happening again—four consecutive no POSTs this week.
To get my PC back on:
- Restarting via the front panel button sometimes works after several failures (rare).
- Power cycling off and on through the front panel helps a few times.
- A full power cycle usually succeeds but isn’t guaranteed; sometimes two cycles are needed.
Potential Clues to Consider:
- Debug LEDs: On boot, BOOT LED lights first, then VGA, and together they turn off after the logo appears. When no POST occurs, BOOT LED turns on then off, followed by VGA turning on, then BOOT LED comes back on—leading to failure. (Video attached.)
- NVMe M.2 health: 94% health in OCCT; still functional, command prompt reports OK.
- GPU performance: Normal in Monster Hunter Wilds, but very low FPS in Tavern Master (~10% usage).
- Possible causes: Outdated BIOS, motherboard issues, power supply problems, or unstable PSU.
My Hypotheses:
- BIOS version might be affecting startup stability.
- Power supply or PSU instability could trigger intermittent failures.
- Hardware faults (motherboard, GPU, SSD) are less likely given normal operation otherwise.
Anyone else noticed similar patterns? Your insights would be invaluable. Thank you!
Check if it involves the GPU and whether it remains covered under warranty. Confirm your drivers are current and test various PCIe slots and power cables.
I believe the issue could be linked to the GPU itself. Despite my ability to run demanding games smoothly, I still faced problems when testing the hardware in-store. After updating all relevant drivers and having the GPU under warranty, it was returned for inspection. The test results confirmed its good performance. Bringing the full system to the store helped verify stability, but since the problem only appears intermittently, it booted normally several times before resuming. Your persistence in checking both home and professional environments is valuable.
They already had a check done, so the issue isn’t there. I assumed the problem was with the GPU since the VGA light relates to it. Have you tried using another power cable?
I swapped out the cable and adjusted its slot on the PSU. I also reverted the BIOS settings, turning off the XMP profile and CSM. The system can now boot, but I’ll keep an eye on it to check if the issue continues. Appreciate your guidance.
I've tried fixing the issue by swapping out the PSU cable, repositioning all parts, reinstalling Windows, and updating drivers. It seems a faulty GPU driver might be the root cause. Here’s the breakdown: After a Windows reinstall (before adding the GPU driver), my PC booted and restarted multiple times without trouble while installing motherboard drivers and tweaking UEFI settings. During Adrenalin 25.3.1 installation, all monitors dropped mid-process. I had to restart via the front panel, but it didn’t power on properly. After rebooting, only one monitor reconnected after the GPU driver update, before the fix. Using AMD Cleanup and reinstalling the driver with Adrenalin 24.12.1 helped, but the problem persisted. Now, once Windows is up, everything functions smoothly—games, streaming, tests run without issues. I’ve adjusted many settings (Fast Boot, UEFI Trusted Computing, Secure Boot, etc.), yet the boot failure remains. I’m still unsure which step triggered the issue. Once the system starts, it works flawlessly; I’m curious if repeatedly pressing the restart or a single power button press could harm my hardware. Note: I’m using UEFI, not BIOS, but that’s just to be safe.