Windows 25H2 makes 32 bytes offset after upgrade?

[Delly10 0]

Possible Link Between Windows 11 24H2/25H2 and Changed NVMe Partition Alignment ?

I’d like to share an experience that I haven’t seen documented elsewhere, but which may be relevant for anyone running newer SSD/NVMe drives on Windows 11.

• Background: On Windows 11 23H2 in 2024 my Corsair NVMe drive ran stable and fast. Later that year, the drive suddenly failed with BSOD and died eventually , and I suspect heat was the cause, since most motherboards place the NVMe socket close to the GPU with poor airflow. I relocated my new NVMe drive using an extension cable near a case fan, which lowered temps significantly.
• Performance and alignment: I discovered that partition alignment (especially on the C: system drive) is critical for SDD/NVMe performance. With proper 4K alignment I achieved full speed and lower temps.
• Windows 11 24H2/25H2: After upgrading to 24H2 this year I experienced (not related to this topic) instability. On 25H2 upgrade things improved overall, but I noticed that partition alignment had changed from 4096 to 32‑byte after the 25H2 upgrade ! With the new misalignment at 32‑byte offset the performance dropped and temps rose by 4–5 °C. This caused poor performance and higher temps. After manually restoring 4K alignment, everything returned to normal.
• Suspicion: I suspect that Windows 11 feature updates may alter partition alignment on the system drive(Microsoft standard of 32 byte and 1K byte. This could be dangerous for NVMe drives, since misalignment forces the controller to work harder, increases heat, and may shorten lifespan.

Questions for the community​

• Has anyone else seen partition alignment change after Windows updates?
• Could this be related to the known SSD/NVMe issues in 24H2 also?
• Is there a way to automatically verify or enforce alignment after major updates?
• Using msinfo32:
  
  1. Press Win + R, type msinfo32, press Enter.
  2. Go to Components → Storage → Disks.
  3. Look at “Partition Starting Offset.” Divide this number by 4096.
     
     • If the result is an integer, the partition is correctly aligned.
     • Example: 1,048,576 ÷ 4096 = 256 → aligned.
     • Example: 32 ÷ 4096 = 0.0078 → misaligned.

Cheers, Lars