After BIOS update SSD performance is cut in half

[Chipcraft]

HP ZBook 15 G5 Mobile Workstation.

After the last BIOS update (to 1.32.0) my SSD drives run at about half speed (read and write). It seems the PCIe interface may be sharing lanes now with the GPU. I don't see any settings in the BIOS related to PCIe lane usage... how do I fix this? or how do I roll-back the BIOS to the previous version?

thank you.

[Samrit26]

Hello,

That’s a very good observation — and you’re right to suspect PCIe lane allocation changes introduced in BIOS 1.32.0. This specific version for the HP ZBook 15 G5 included a firmware-level modification to the platform controller hub (PCH) power management and PCIe ASPM (Active State Power Management) behavior, which can, in certain configurations, cause NVMe SSD throughput to drop to roughly half of normal.

Let’s go over this methodically.

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1. Verify the actual link speed

First, confirm whether the SSD link has actually been renegotiated to a lower PCIe width or speed:

1. Open Device Manager → Storage Controllers → [Your NVMe Controller] → Properties → Details → Link Speed (or use HWiNFO64 for more detail).

2. You’ll likely see PCIe 3.0 x2 instead of the expected PCIe 3.0 x4.
   That confirms BIOS lane reallocation or ASPM throttling.

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2. Check BIOS settings

Even though HP does not expose explicit PCIe lane assignment controls, you can check a few toggles that influence this indirectly:

1. Reboot and enter BIOS (F10).

2. Under Advanced → Power Management Options, ensure:

   • Runtime Power Management: Disabled

   • Extended Idle Power States: Disabled

   • M.2/PCIe SSD Power Management: Disabled (if available)

3. Save and exit, then retest disk performance.

If performance restores, it’s the ASPM policy introduced in 1.32.0.

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3. If the issue persists: roll back BIOS

HP allows secure rollback as long as the “BIOS Rollback Policy” option remains enabled in BIOS Security.

Steps to safely roll back:

1. Go to the HP Support site for ZBook 15 G5 → “Software, Drivers and Firmware.”

2. Expand the BIOS section and locate version 1.31.0 or earlier.

3. Download the previous BIOS .exe file.

4. Create a BIOS recovery USB:

   • Run the downloaded file on a Windows PC.

   • Choose Create Recovery USB (select a blank USB drive).

5. Insert the USB drive into the ZBook.

6. Power on and repeatedly tap Win + B, then press Power for ~3 seconds, and release Power while holding Win + B.
   → The system will enter BIOS recovery and flash from the USB image.

7. Once the rollback completes, verify BIOS version (F10 → Main tab).

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4. After rollback

Once on 1.31.0, re-run your SSD benchmark. You should see restored speeds and PCIe 3.0 x4 link width.

After confirming stability, I recommend turning HP Sure Start Automatic BIOS Update off temporarily in BIOS until HP releases a newer version (1.33.x or later) addressing this regression.