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docs: add PN51 stability testing notes
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-02-22 00:24:28 +01:00

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ASUS PN51 Stability Testing

Overview

Two ASUS PN51-E1 mini PCs (Ryzen 7 5700U) purchased years ago but shelved due to stability issues. Revisiting them to potentially add to the homelab.

Hardware

pn01 (10.69.12.60) pn02 (10.69.12.61)
CPU AMD Ryzen 7 5700U (8C/16T) AMD Ryzen 7 5700U (8C/16T)
RAM 2x 32GB DDR4 SO-DIMM (64GB) 1x 32GB DDR4 SO-DIMM (32GB)
Storage 1TB NVMe 1TB Samsung 870 EVO (SATA SSD)
BIOS 0508 (2023-11-08) Updated 2026-02-21 (latest from ASUS)

Original Issues

  • pn01: Would boot but freeze randomly after some time. No console errors, completely unresponsive. memtest86 passed.
  • pn02: Had trouble booting — would start loading kernel from installer USB then instantly reboot. When it did boot, would also freeze randomly.

Debugging Steps

2026-02-21: Initial Setup

  1. Disabled fTPM (labeled "Security Device" in ASUS BIOS) on both units
    • AMD Ryzen 5000 series had a known fTPM bug causing random hard freezes with no console output
    • Both units booted the NixOS installer successfully after this change
  2. Installed NixOS on both, added to repo as pn01 and pn02 on VLAN 12
  3. Configured monitoring (node-exporter, promtail, nixos-exporter)

2026-02-21: pn02 First Freeze

  • pn02 froze approximately 1 hour after boot
  • All three Prometheus targets went down simultaneously — hard freeze, not graceful shutdown
  • Journal on next boot: system.journal corrupted or uncleanly shut down
  • Kernel warnings from boot log before freeze:
    • TSC clocksource unstable: Marking clocksource 'tsc' as unstable because the skew is too large — TSC skewing ~3.8ms over 500ms relative to HPET watchdog
    • AMD PSP error: psp gfx command LOAD_TA(0x1) failed and response status is (0x7) — Platform Security Processor failing to load trusted application
  • pn01 showed neither of these warnings and remained stable

2026-02-21: pn02 BIOS Update

  • Updated pn02 BIOS to latest version from ASUS website
  • TSC still unstable after BIOS update — same ~3.8ms skew
  • PSP LOAD_TA still failing after BIOS update
  • Monitoring back up, letting it run to see if freeze recurs

Benign Kernel Errors (Both Units)

These appear on both units and can be ignored:

  • pcie_mp2_amd: amd_sfh_hid_client_init failed err -95 — AMD Sensor Fusion Hub, no sensors connected
  • Bluetooth: hci0: Reading supported features failed — Bluetooth init quirk
  • Serial bus multi instantiate pseudo device driver INT3515:00: error -ENXIO — unused serial bus device
  • ata2.00: supports DRM functions and may not be fully accessible — Samsung SSD DRM quirk (pn02 only)

Next Steps

  • Monitor pn01 stability (fTPM disabled, no other changes needed)
  • Monitor pn02 stability after BIOS update
  • If pn02 continues to freeze, try adding tsc=unstable kernel parameter
  • If pn02 still freezes, may be a hardware defect on that specific unit
  • Once stable: add second RAM stick back to pn02, reinstall with NVMe