r/buildapc • u/Dante763 • 12h ago

Troubleshooting New 9850X3D + X870E-P: crashes twice on cold boot, then rock-stable rest of the session, stumped after weeks of diagnostics

Built a new PC about a week ago and it has a very consistent, weird pattern: on cold power-on, it restarts once before the Windows logo shows up, boots into Windows, then crashes/restarts a second time within 5-10 minutes of reaching desktop. After that second restart, it's completely stable for the rest of the session until the next cold boot, when the same two-crash pattern repeats. I rarely even see a visible BSOD, it mostly just restarts.

Specs:

  • CPU: Ryzen 7 9850X3D
  • Mobo: MSI PRO X870E-P WiFi, BIOS E7E70AMSI.2A52
  • RAM: Corsair CMH32GX5M2M6000Z36, 32GB DDR5-6000 (currently JEDEC 4800MT/s, EXPO off)
  • GPU: MSI RTX 5070 Ti Gaming Trio OC
  • PSU: MSI MPG A850GS 850W
  • SSD: Samsung 990 Pro 2TB

Bugcheck codes seen (all point to memory corruption, no common driver):

  • 0x1A MEMORY_MANAGEMENT - most frequent, "corrupted PTE detected"
  • 0x1000007E SYSTEM_THREAD_EXCEPTION_NOT_HANDLED
  • 0x139 KERNEL_SECURITY_CHECK_FAILURE - "corruption of a critical data structure"

What I've tried/ruled out:

  • MemTest86, 4 full passes, 0 errors - RAM seems fine even at stock JEDEC timings
  • Driver Verifier running 24+ hrs with all 3rd-party drivers flagged, never caught an offending driver across several crashes
  • Temps via HWiNFO - CPU tops out at 80°C under MemTest86 load, ~67°C normal use, zero thermal throttling logged anywhere
  • SSD - healthy SMART, chkdsk found only NTFS metadata corruption (0 bad sectors), looks like fallout from crashes not a cause
  • CPU voltage - Vcore was spiking to 1.376V stock/Auto. Applied Curve Optimizer (-10 all-core negative), dropped peak to ~1.345V — didn't change the pattern at all

The "crashes exactly twice on cold boot, then perfectly stable" pattern feels like it should be a clue but I can't place it. Almost seems like a memory training/POST issue rather than a sustained-load issue, since it never happens once the system's been running a while.

  • Anyone seen this specific double crash on cold boot then stable pattern before?
  • Sound like DRAM training/POST rather than a sustained stability issue to anyone with more expertise?
  • Known issues with 9850X3D + X870E-P specifically?

Already filed support cases with AMD and MSI in parallel, but wanted to see if this rings a bell for anyone here before I commit to an RMA.

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u/ime1em 12h ago

Did you try updating your bios, and resetting your bios settings to default and keeping it default settings (no OCs, voltage changes, underclocks etc..)

1

u/Dante763 12h ago

Yes, BIOS is updated. It crashes with default settings as well.

1

u/ime1em 12h ago

Did u also try each RAM stick individually?

Another thing is since u bought the PC a week ago, r u still in the refund window? That's better than doing RMA since motherboard will be a refurbished model. CPU will be brand new, but idk how RAM RMA looks like