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HPE ProLiant fans stuck at full speed even when the server is cool? If you've installed third-party drives, here's exactly why it happens — and the clean, supported way to fix it.
Last updated: 2026
If you manage a data center, a server room, or even just a homelab, you already know the soundtrack: the persistent, jet-engine roar of server cooling fans. While a certain amount of noise is expected, it can become a major headache when server fans ramp up to 100% and refuse to spin down — especially when the server isn't even running hot.
If you run HPE ProLiant servers (like the MicroServer Gen11) and have ever swapped in third-party, non-HPE hard drives, you might be very familiar with this exact scenario. An insightful discussion on the HPE Community Forums shed light on why this happens and, more importantly, how one clever IT professional managed to solve it.
A quick word before we dive in
We do not endorse the use of non-HPE drives in HPE servers, and we do not sell non-HPE drives for use in HPE servers. We strongly encourage anyone running HPE servers to use authentic HPE parts to ensure optimal compatibility, reliable warranty support, and correct thermal performance.
The history of the issue
The "100% fan speed" quirk isn't new. IT professionals have reported this behavior across various ProLiant generations for years. HPE's Integrated Lights-Out (iLO) management engine relies on thermal sensors to decide how fast the chassis fans should spin: if a sensor reports a high temperature, iLO spins the fans up to protect the hardware. But when standard third-party hard drives are installed, many users have seen the fans screaming at maximum RPM even when the drives are practically idling and cool to the touch — wasting power and patience without a clear reason why.
The root cause
A community member named pfavr dug into the software stack to find out exactly why this was happening on their MicroServer Gen11 equipped with third-party 24 TB drives. According to that investigation, the Agentless Management Service (AMS) — specifically the cpqide agent — reports drive temperatures to iLO, and when it detects a non-HPE drive it inflates the reported temperature by roughly 25 °C. iLO reads that inflated figure, genuinely believes the drives are overheating, and triggers the fans to spin at maximum speed as a programmed safety response.
The open-source workaround
Because the root cause lies in the telemetry handoff between AMS and iLO, pfavr developed an open-source workaround that intercepts and corrects the data. Instead of risky binary patching, the script corrects the temperature reading before iLO sees it. Fed the true, uninflated temperature, iLO recognizes the hardware is safe and lets the fans idle normally (dropping back to a whisper-quiet 20% in the author's case). The author describes the fix as clean, easily reversible, and simple to deploy.
It's always great to see the IT community come together to reverse-engineer a quirk, write a custom patch, and share it with everyone else. If you're comfortable tinkering under the hood of a lab machine, this workaround might be the peace and quiet you've been looking for.
The supported fix: genuine HPE drives
The community workaround is clever, but it treats a symptom. The reason genuine HPE drives don't cause this problem in the first place is that the same AMS-to-iLO telemetry chain reports their temperature accurately: HPE drives carry firmware that iLO authenticates, so iLO reads true temperature, wear, and predictive-failure data and cools the server appropriately. Swap the third-party drives for genuine HPE drives and the fans return to normal on their own — no scripts, no patches, and with full warranty coverage and iLO health monitoring intact.
| Behavior | Genuine HPE drive | Third-party drive |
|---|---|---|
| Temperature reported to iLO | Accurate | Can be inflated (~+25 °C via AMS), triggering max fans |
| Fan behavior | Normal; spins down when cool | Can run at 100% even when idle |
| iLO health & wear monitoring | Full, with predictive-failure alerts | Limited; may raise "unsupported drive" warnings |
| Warranty & support | Covered by HPE | Not covered |
If the loud fans pushed you to look for a fix, the cleanest one is to populate the server with the drives it's designed for. Browse genuine HPE server hard drives — SAS and SATA — and HPE server SSDs, or start from your exact model on our HPE parts by server model page.
Frequently asked questions
Why are my HPE ProLiant server fans running at 100%?
HPE's iLO management engine sets fan speed from temperature sensors, so if a component reports a high temperature, iLO spins the fans up to protect the hardware. A common cause of unexpectedly loud fans is a drive that reports an inflated temperature to iLO — often a third-party (non-HPE) drive — which makes iLO treat the drive as overheating even when it is cool.
Do third-party (non-HPE) drives cause HPE server fans to speed up?
They can. Many administrators have found that installing non-HPE drives in a ProLiant server makes the fans run at maximum RPM even when the drives are idle and cool. Genuine HPE drives carry firmware that iLO authenticates and reads accurate temperature and health data from, so the fans behave normally.
What causes HPE servers to over-report third-party drive temperatures?
According to a community investigation on the HPE forums, the Agentless Management Service (AMS) — specifically its cpqide agent — reports drive temperatures to iLO, and when it detects a non-HPE drive it adds roughly 25 °C to the reading. iLO then treats the drive as overheating and drives the fans to full speed.
How do I stop the loud fan noise on an HPE ProLiant server?
The supported fix is to use genuine HPE drives, which report accurate temperatures to iLO so the fans spin down when the hardware is cool. If you are running third-party drives in a lab environment, a community-developed, open-source script can correct the inflated temperature reading before iLO sees it, allowing the fans to idle normally.
Does using genuine HPE drives fix the fan noise?
Yes. Because genuine HPE drives report accurate temperature and health data through the AMS and iLO telemetry chain, iLO cools them appropriately and the fans return to normal, quiet operation — with the added benefit of full iLO monitoring, predictive-failure alerts, and warranty support.
Is the community GitHub fan fix safe to use?
The community fix corrects the drive temperature reported to iLO rather than modifying firmware, and its author describes it as clean and easily reversible. It is an unofficial, third-party workaround, though, so it is best suited to homelab and testing use — production systems should run genuine HPE drives for supported, predictable thermal behavior.
Which HPE servers are affected by this fan-speed issue?
Administrators have reported high fan speeds with non-HPE drives across many ProLiant generations over the years, including recent models like the MicroServer Gen11. The underlying behavior — iLO raising fan speed in response to a reported drive temperature — applies across the ProLiant line.
The bottom line
The 100% fan quirk with third-party drives comes down to one thing: iLO acting on an inflated temperature reading. For a lab or homelab where you're comfortable tinkering, the community's open-source script is an elegant way to quiet things down. For a production HPE ProLiant server, the right fix is genuine HPE drives, which report accurate temperatures, keep full iLO monitoring and warranty coverage, and let the fans idle the way they should. Not sure which drives your server takes? Find parts for your exact model or contact our team and we'll confirm the right genuine HPE drive before you order.
