Z2 Tower G9 fails CPU fan test

[hansep53]

My new Z2 Tower G9 machine (purchased on 30.12.2024) CPU fan does not pass Bios test "Important: The test detected a speed problem with the CPU fan and the fan may need to be replaced". The fan was replaced, then the motherboard too...the problem persists?. There is also some whining, power supply?, would replacing the power supply help with both problems?

[NonSequitur777]

@hansep53,

Welcome to our HP Community forum!

So, despite replacing both the CPU fan and motherboard, you continue having to deal with a persistent CPU fan speed issue in your HP Z2 Tower G9. The power supply's whining noise most definitely raises concerns about your power supply as a potential factor.

Possible Causes & Troubleshooting Steps:

1. BIOS & Firmware Updates:

• Ensure the BIOS is up to date. HP frequently releases updates that resolve fan detection and sensor issues.
• Update Intel ME firmware as well, since it interacts with system sensors.
• Reset the BIOS to defaults after updating to clear any conflicting settings.

 

2. Fan Connection & RPM Signal Issues:

• The Z2 Tower G9 uses a 4-pin PWM CPU fan -please confirm it's plugged into the correct CPU_FAN header, not a chassis fan header.
• If the BIOS isn’t detecting proper RPM, try a known-working third-party PWM fan (like Noctua) to rule out incompatibility issues.
• Check if the fan is spinning at startup—some BIOS fan tests require an initial spin-up period to pass.

 

3. Power Supply (PSU) as a Possible Culprit:

• The whining noise could indicate coil whine or PSU voltage regulation issues. If the PSU is providing unstable power, it could cause erratic fan behavior.
• Test with a known-good, HP-compatible PSU (preferably the same wattage or higher). If the issue disappears, the original PSU is faulty.

 

4. Motherboard or Sensor Defect (Even After Replacement?):

• Since the motherboard was replaced, is the replacement new or refurbished? If refurbished, a lingering defect is possible.
• Run HWMonitor or HWiNFO in Windows to check real-time fan RPM values. If they fluctuate abnormally, it might be a sensor issue.

 

Next Steps:

• Step 1: Update BIOS and firmware.
• Step 2: Try a different, known-working PWM fan.
• Step 3: Test with another compatible PSU to see if it resolves both fan issues and whining noise.
• Step 4: If all else fails, request a brand-new replacement motherboard from HP support.

Kind Regards,

NonSequitur777

[hansep53]

Thank you very much for your quick response and the many solution options. I updated the original Bios to the latest one as early as January 2025. HP support sent a technician from their authorized service center who first installed a new fan and a week later changed the motherboard Rev, 1.00 => Ver. 0G, did not help but now they have already been thinking for 8 days at higher levels what to do next? The CPU fan is in the right connector, the power supply is indeed whining like in the other post here. What I do must take into account HP's 3 year warranty.

[NonSequitur777]

@hansep53,

If at all possible, try out a replacement (new) power supply.

Kind Regards,

NonSequitur777

[hansep53]

Now, 14.02.2025, the power supply, processor and processor fan were replaced. It still does not pass the CPU fan test. No more replacing Corsair Dimm memories 32 GB. HP is going to the engineer level after a service technician has been here three times to replace parts. The new power supply whines in the same way as the previous one, in waves and intermittently. The sound of the rear case fan has been varying in waves all the time even though the device is not being used, i.e. in sleep mode.

[hansep53]

So without changing any more Dimm memories, Corsair brand

[NonSequitur777]

@hansep53,

Something doesn't add up.  You really shouldn't have this issue anymore.

At this point in time, I would request either to get a whole new system or getting a full refund.

Kind Regards,

NonSequitur777

[hansep53]

Thanks for your comment and help, I've been thinking the same thing because this computer doesn't meet the technical specifications and doesn't pass the CPU fan test. Otherwise it has worked flawlessly.
I'm waiting for HP support to respond, I sent them the BIOS error log and the audio files made with my cellphone's voice recorder.

[hansep53]

Correction: The DIMMs are indeed 16GB Micron 5600MHz

[NonSequitur777]

@hansep53,

In my professional opinion, given all the troubles you have been through, you have clearly reached the point of justly requesting either a refund or a new system.

Kind Regards,

NonSequitur777