ProDesk 600 G5 CPU Fan control

[msssm]

ProDesk 600 G5 with i7-9700.

How can I change the CPU fan control? It seems to be integrated and not visible to the system? At least Linux lm-sensors doesn't see any fan or rpm value.

The problem is, the fan is quite sensitive and turns to max even around 78°C package temperature and above. On idle it's quiet but for every very simple load on single cores the fan turns up to max. It is very noisy.

Hardware is absolute clean and freshly mounted with thermal paste. The CPU keeps cool, but the fan seems to be to aggressive. All older HP desktops I owned like EliteDesk 800 G1 were absolutely quiet, but this here is the most noisy.

Back to linux. I don't see anything in sensors or fancontrol. I would try intel-undervolt now, but actually 78°C is not much and I never see higher temperatures than about 80°C looking at:

intel-undervolt measure

[NonSequitur777]

@msssm,

Welcome to our HP Community forum!

Why Fan Control Doesn’t Work in Linux:

• HP business desktops (such as the ProDesk line) don’t expose fan RPM or control via standard ACPI or SMBus interfaces, which means tools like lm-sensors or fancontrol won’t detect the fan or its speed sensors.

• Fan profiles are hardcoded into the BIOS/EC firmware, and not user-configurable.

• BIOS Setup (F10) for this model typically lacks advanced thermal or performance tuning options.

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Why the Fan Seems Overly Aggressive:

• HP likely uses a conservative thermal policy prioritizing hardware longevity and assumes office use cases (low background noise).

• The i7-9700, although within TDP limits, can still produce high transient heat spikes on 1–2 cores, triggering short-term fan bursts.

• Even small workloads that push temps into the upper 70s °C will often result in full-speed fan spin-up on these models.

---

User-Verified Workarounds & Recommendations:

1. Undervolting (as you’re considering):

   • Using intel-undervolt is a smart workaround and if you can get it to work, can reduce package temperatures by 5–15°C depending on the chip.

   • You may also see less frequent fan spin-ups at the same workload if temps remain under HP’s internal ramp-up threshold (~75–77°C).

2. Replace the Stock Fan with a High-Quality PWM Fan:

   • HP uses a proprietary 4-pin PWM fan with standard pinout, so you can try replacing it with a quieter model like:

     • Noctua NF-A9 PWM (92mm) — highly recommended.

     • Arctic F9 PWM PST — cheaper alternative.

   • You’ll need to ensure:

     • Same connector (PWM 4-pin)

     • Similar CFM and static pressure (HP’s default fans are tuned for the small airflow in the SFF chassis)

   • While the new fan still responds to HP’s fan curve, it may do so more quietly, reducing acoustic annoyance.

3. BIOS Update (Slim Hope):

   • Occasionally, HP BIOS updates revise thermal behavior.

   • It’s worth checking if a new BIOS version is available that may tone down the fan ramp.

4. Thermal Padding & Case Ventilation Mods:

   • Improving your overall case airflow (adding one or more cooling fans or vent mods) helps reduce chassis heat buildup, which is often interpreted by the thermal sensor as justification for fan ramping.

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What Doesn’t Work:

• fancontrol, pwmconfig, or lm-sensors adjustments (not supported by BIOS/EC).

• Disabling fan control in BIOS — not an option.

• Windows tools like SpeedFan — these also don’t work with HP EC firmware.

---

Caution:

Avoid using third-party EC override tools or modded BIOS in HP business desktops — HP locks firmware signatures tightly, and such efforts may brick the system or prevent BIOS updates and support.

---

Conclusion:

The aggressive fan ramp-up behavior on your HP ProDesk 600 G5 is unfortunately a limitation of HP's firmware, which doesn’t expose fan control to the OS. Your best options are to try t undervolt the CPU using intel-undervolt and consider replacing the stock fan with a quieter PWM fan like the Noctua NF-A9. These changes won’t give you manual fan control but can reduce how loud it gets under light workloads.

Kind Regards,

NonSequitur777

[msssm]

Hi, thank you for the answer. Was that some standard template or a real answer to my issues?

Anyway, I blindly purchased the Noctua 92mm and got to know it does not fit as the machine uses a 80mm fan. So I ordered another 80mm model which is the Noctua NF-A8 PWM 80mm. I don't expect that much noise reduction from the better fan design, but I expect that Low noise adaptor (L.N.A.) will do as it converts a 2200rpm max into 1750rpm.

About undervolting, I tried that as well but it seems to be restricted by the HP board, writing the values via intel-untervolt fails. I just also tried it on my HP Zbook, restricted as well.

Still waiting for the new fan and going to report back here..

Finally this is one argument against using HP in future and better going back to custom boards with real access to voltage and fan control.

I purchased HP business models the last years for not having to deal with all these details. I don't want to spend time with over/under clocking, custom ventilation and cooling. And I love the Small Form Factor SFF design being small but still providing an optical drive and PCIe slots. SFF is not often seen on custom hardware...

And I always purchased 4 year old business hardware from enterprise sellings because of the good price for complete systems.

But if I need to buy additional expensive fans and controlers to change the noise and PWM rpm, it is not worth the effort..

This is the first model being too noisy in standard configuration for being used in an office.

[NonSequitur777]

@msssm,

Yes, guilty as charged: part of my response was indeed part of a standard response -my bad.

Please follow up once you got the new fan and share what difference, if any, there is.

Kind Regards,

NonSequitur777

[msssm]

For now I kept the original fan and just added the Low Noise adapter to reduce rpm. It does not seem to have circuits but only some voltage lowering, which results in lower max speed but actually does not have much reduction on lower speeds. That's ok. Noise is reduced a lot, it is usable now.

I'm going to replace the fan as well when I have the Noctua 80mm model, because it might reduce noise a bit more...

Interestingly the maximum temperatur of the CPU on high load does not increase much with the lowered fan speed...

However I'm not sure if I keep buying business machines in future if they are not perfectly constructed as is and because I don't have enough customizing options on the firmware and also hardware...

[NonSequitur777]

@msssm,

Thank you for following up: I am interested to know exactly what this 'low noise adapter' is and how/where you installed it.

Kind Regards,

NonSequitur777

[msssm]

It's a 4 PIN adapter cable that is installed between the mainboard socket and the fan. It reduces for the 80mm model the fan speed from 2200 to 1750 rpm. From what I know it's only lowering the voltage and does not reclock the PWM signal or something.

[NonSequitur777]

@msssm,

Something like this, then: Amazon.com: Noctua NA-SRC7, 4 Pin Low-Noise Adaptor Cables for PC Fans (Black) : Electronics.

Good to know these adapter cables exist!

Kind Regards,

NonSequitur777

[msssm]

Yes, and good to know these adaptors can be purchased separately if next time I like to tune the original fan only (like I have done now but going to replace the fan for the Noctua fan as well....)

They also have more flexible PWM controlers like the NA-FC1 that can be adjusted by a control wheel and also do some PWM re-clocking, not only lowering voltage, from what I read there...

Finally it would have also been an option to change the CPU for a lower TDP like the T-series (i7-9700T) having 35W TDP only. But I always need the maximum available CPU. I just preferred the 9700 against the 9900 because of the better price. 9900 are far too expensive and rarely offered. It would have 65W TDP as well just like the 9700. From what I understand, any 65W TDP CPU would have exactly the same heat generation like comparing the i5-9400, i5-9500, i7-9700 and also i7-9900. So no (heat-)advantage of using some i3 or i5, only the T versions would really reduce the heat while having less CPU power....

As the ProDesk 600 G5 is designed for 65W TDP I took the maximum with that TDP. For sure I'm not taking a K series with 95W.

But I had the noise issue with 65W... and got it somehow solved now with Noctua products. Thanks for that hint.

All other ideas about installing a complete new cooling or even water based cooling would be far more expensive, and I purchase used HP hardware for the good price, for not needing additional custom hardware.