HP Z2 G8 Workstation does not power off completely unless PCI Express Power Management is enabled

[MRGEOCAD]

Hello everyone,

I am experiencing a very unusual power management issue with my HP Z2 G8 Tower Workstation and I would appreciate any advice or confirmation from HP if this is expected behavior.

System configuration:
- HP Z2 G8 Tower Workstation
- Intel Core i7-11700K
- 32 GB RAM
- NVIDIA RTX A2000 (factory installed)
- Windows 11 Pro 25H2 (Build 26200)
- BIOS Version: T50 01.06.12

Problem:

The workstation does not complete either a normal shutdown or a restart.

Shutdown behavior:
When I select "Shut Down" in Windows, Windows closes normally and the monitor turns off. However:
- the power LED remains ON
- all system fans continue spinning
- the workstation never reaches a complete S5 (soft off) state
- I must hold the power button for about 5 seconds to completely turn it off.

Restart behavior:
When I select "Restart", Windows shuts down correctly, but the system never powers back on. Instead, it remains stuck with the power LED continuously illuminated and the fans running. The workstation never completes the reboot process and requires a forced power-off.

After extensive troubleshooting, I discovered that enabling the following BIOS option completely resolves BOTH issues:

PCI Express Power Management

With this option ENABLED:
- Shutdown works correctly.
- Restart also works correctly and the system powers back on normally every time.

With this option DISABLED:
- The shutdown problem immediately returns.
- The restart problem also immediately returns.

Troubleshooting already performed:

• Updated NVIDIA RTX A2000 driver to the latest available version.
• Installed the latest Intel Management Engine driver.
• Installed the latest Intel chipset drivers available from HP.
• Updated Windows completely.
• BIOS is already running version T50 01.06.12 (latest available on the HP support page).
• Attempted to update the BIOS again, but the update failed with an internal error because the same BIOS version was already installed.
• Checked BitLocker status before attempting the BIOS update.
• Ran:
- powercfg /a
- powercfg /requests
- powercfg /devicequery wake_armed
- powercfg /energy
• No process or device is preventing shutdown.
• The workstation is in its original factory hardware configuration.
• No hardware has been replaced or modified.
• Installed the latest available Intel Management Engine and chipset updates from the HP support website without any improvement.

Additional information:

The issue has been present for several months.

The workstation is completely stable during normal operation and under heavy workloads. The only problem affects the power-off and restart sequence when PCI Express Power Management is disabled.

Questions:

1. Is this a known BIOS or firmware issue affecting the HP Z2 G8?
2. Is PCI Express Power Management expected to be enabled by default on this platform?
3. Could this indicate a motherboard firmware issue or a PCIe power management compatibility issue with the NVIDIA RTX A2000?
4. Has anyone with an HP Z2 G8 experienced the same behavior?

Any suggestions from HP engineers or other HP Z2 G8 owners would be greatly appreciated.

Thank you.

[NonSequitur777]

@MRGEOCAD,

Welcome to our HP Community forum!

Kudos: this is a thoroughly documented and highly technical breakdown. Your isolated testing confirms a definitive link between the system's power state transition (S5 soft-off) and Active State Power Management (ASPM) over the PCIe bus.

1. Is this a known BIOS or firmware issue affecting the HP Z2 G8?

Yes. HP has officially recognized this exact behavior on the HP Z2 Small Form Factor and Tower G8 Workstations: HP Z2 Small Form Factor and Tower G8 Workstations - Multiple Issues May Be Observed When Updating or....

HP released a technical advisory specifically addressing the issue where G8 workstations fail to complete the shutdown or reboot cycle (leaving fans spinning and the power LED illuminated) if certain PCIe states are left unmanaged by firmware. The formal engineering resolution provided by HP for this platform is to ensure that PCI Express Power Management is toggled to Enabled within the F10 BIOS settings.

2. Is PCI Express Power Management expected to be enabled by default on this platform?

Yes, it is the factory-default and intended operating state. On workstation-class platforms like the Z2 G8, PCIe Power Management (which governs native ASPM) is designed to be active by default.

When it is manually disabled (or disabled via an aggressive OS power profile), the motherboard stops negotiating low-power transitions with connected PCIe devices during the ACPI teardown process. Because the system cannot successfully command the PCIe layout to step down into an L1/L2 link state, the motherboard hangs right at the transition boundary to the S5 state—keeping the power rails energized, the fans spinning, and the LED lit.

3. Could this indicate a motherboard firmware issue or a PCIe power management compatibility issue with the Nvidia RTX A2000?

It points directly to a protocol handshake limitation between the motherboard firmware and the PCIe device's onboard controller (in your case, the RTX A2000), rather than failing hardware.

Graphics cards heavily rely on Active State Power Management to throttle power when transitioning out of the OS environment. When you disable PCI Express Power Management in BIOS, you force the system to bypass native ASPM. Without that software handshake, the motherboard’s embedded controller cannot verify that the RTX A2000 has safely unlinked from the bus. As a safety precaution against data corruption or hardware voltage spikes, the motherboard refuses to cut the main 12V rail, resulting in the "stuck fans and LED" behavior you observed.

4. Has anyone with an HP Z2 G8 experienced the same behavior?

Many users running highly customized power profiles or legacy OS configurations on the G8 series have run into this. Most reports of "fans spinning at 100% after shutdown" or "system hanging on black screen reboot" on the HP Support Community for the Z2 G8 trace directly back to this specific configuration.

Summary & Recommendation:

As far as I can ascertain, your hardware is entirely healthy, stable, and performing as engineered. The behavior you ran into is an expected design limitation when the motherboard is instructed to drop PCIe power coordination.

The definitive fix is to leave PCI Express Power Management ENABLED in your F10 BIOS. Since you are running a clean, factory-hardware configuration, keeping this enabled is optimal for system longevity, power consumption, and proper S5 power-cycling.

Btw, are you experiencing any other power-related anomalies, such as the system unexpectedly waking from sleep, or does everything else run perfectly when this setting is enabled?

Kind Regards,

NonSequitur777