When booting up an HP computer, you may encounter a “System Fan (90B)” error message. This type of problem often occurs during the startup self-test phase of laptops or desktops. When it occurs, many people worry that the fan is broken, the motherboard is faulty, or even that the computer can no longer be used.

In fact, a 90B error message from an HP fan usually indicates that the system has detected an abnormal fan speed, insufficient cooling capacity, or a problem with fan control. This article will help you quickly resolve this issue by addressing common causes and providing specific solutions.

1. What does the HP fan 90B error message mean?

When an HP computer displays error 90B during startup, it generally indicates that the system has detected a malfunction in the cooling fan, which is insufficient to meet the current hardware’s cooling requirements.
Simply put, the computer detects this during its self-test.

• The fan is not rotating properly;
• The fan speed is too low;
• Clogged vents caused the temperature to rise excessively.
• The BIOS detected a fan control anomaly.
• An abnormal driver or firmware status is affecting fan scheduling.

If the computer continues to run under poor heat dissipation, the CPU or graphics card temperature will continue to rise, and performance will be affected. That’s why the system will proactively remind the user during the boot process.

II. How to resolve the HP fan 90B error?

To improve efficiency, it is recommended to process the problems in order from simple to complex.

Method 1: First, shut down the computer and check if the ventilation vents are blocked.

If you only occasionally encounter a 90B error, don’t rush to disassemble the computer. First, perform basic checks:
1. Shut down the computer and disconnect the power;
2. Check if the computer’s ventilation vents and exhaust outlets are blocked by dust.

3. Ensure the computer is not placed on surfaces that hinder heat dissipation, such as blankets, sofas, or soft cushions;
4. Restart the computer to see if the error message persists;
Applicable scenarios: The computer has not been cleaned for a long time/the environment is dusty, and recently the fan noise has become noticeably louder and the computer body has become severely overheated;

Method 2: Clean the fan to improve heat dissipation.

If there is significant dust at the heatsink vents, cleaning is recommended. Users with good DIY skills can remove the back cover to clean the fan and heatsink module; if you are not familiar with disassembling, it is recommended to take it to a professional repair shop.
Pay special attention to the following when cleaning:

1. Fan blades;
2. Heat sink fins;
3. Air outlet;
4. Dust around the CPU heatsink module;
After cleaning, many 90B errors caused by dust blockage can be significantly improved.

Method 3: Update BIOS and critical drivers to rule out recognition issues.

Many users overlook the fact that malfunctions in the underlying system drivers or incompatible versions of the motherboard management software can also affect fan status recognition. In such cases, it’s helpful to use Driver Booster to perform a full system scan, focusing on checking the following drivers for any abnormalities.

1. Click the button above to download and install, then open Driver Life and click the “Diagnose Now” option on the “Full Diagnosis” interface;

2. The software will automatically detect existing problems on your computer, such as driver issues, environment repair issues, DLL file issues, runtime library issues, etc. Users can click the “Full Repair” option to batch install drivers and repair existing computer problems, thus restoring the system environment.

Many users are unsure which drivers to update or how to manually distinguish compatible versions. Driver Life enables faster automatic identification and updates, reducing hardware identification problems caused by driver anomalies.

Method 4: Enter BIOS and restore default settings or update the BIOS version

If the fan is not obviously damaged, but the computer keeps reporting error 90B when you turn it on, you can try:
1. Entering the BIOS;

2. Restore default settings;
3. Save and exit, then restart;
if the problem persists, check if there is a BIOS update compatible with your current model. Updating the BIOS can improve fan control strategies and hardware compatibility for some models.

Method 5: Check if the fan is damaged and replace it if necessary.

If your computer exhibits the following symptoms, you should strongly suspect a fan hardware failure:
1. The fan barely spins when the computer is turned on;
2. The fan makes unusual noises, stutters, or friction sounds;
3. Frequent error messages and a rapid increase in chassis temperature;
4. Cleaning dust, updating drivers, and restoring the BIOS do not improve the situation.
In this case, it is recommended to contact official after-sales service or a professional repair technician to check if the fan needs to be replaced. This is especially common with older HP laptops, where fan aging is a frequent issue.

3. Can I still use my HP fan 90B if it reports an error?

It can be used for short-term emergencies, but it is not recommended to ignore it for extended periods.
The reason is simple:

Error 90B often indicates an abnormality in computer cooling. If temperature control fails, it may lead to:
1. Computer slowdown or throttling;
2. Loud fan noise;
3. Automatic restarts or shutdowns;
4. Shortened lifespan of hardware components such as the motherboard and CPU.
If it’s only for temporary use, it’s recommended to back up important data as soon as possible and troubleshoot using the methods described above.

IV. Frequently Asked Questions

1. Does a 90B error on an HP fan indicate a motherboard failure?
Not necessarily. More common causes include dust buildup on the fan, fan aging, poor heat dissipation, or BIOS/driver recognition issues. Motherboard failure is a relatively rare occurrence.
2. Will updating drivers really resolve a 90B error?
If the error is caused by driver malfunctions or unstable hardware management, updating drivers can help.
You can quickly scan and update relevant drivers using Driver Booster . However, if the fan itself is damaged, it will still require repair or replacement.
3. Is a 90B error related to overheating?
Very much so. 90B is a system warning about abnormal heat dissipation, usually related to fan speed, ventilation status, and internal temperature.