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HP Recommended
EliteDesk 800 G2
Microsoft Windows 10 (64-bit)

Hi,

When I boot up my PC, a message of the so-called Error Code 900 

(« CPU Fan not detected (900) CPU Fan is not detected or may have malfunctioned ») appears on my screen.

The fan is perfectly connected to the motherboard, he is clean and there's no dust. He gets a bit noisy if the PC works in a normal state (even if he is high charged).

The CPU is not too hot (less than 75 °C) and the cooling paste is good dispersed on the component.

 

How can I solve this technical problem which annoys me very much ?

 

Thanks for your help.

 

1 ACCEPTED SOLUTION

Accepted Solutions
HP Recommended

HP fans are special, as are dells. , oem are.

first off the BIOS checks the fan  and runs it totally based on thermal demands.

the BIOS also has table showing the relation ship of PWM to RPM ( it sets PWM and if RPM is wrong bam errors)

if they do not match it warns you of  that. by DESIGN.

1:a dead fan.

2: fan is slow. due to lent packed or bearings bad, aka, a bad fan.

3: using non HP fans,

4: plugged in to wrong jack or indexed wrong (off center 1 pin not wired)

5:worse,  bad mobo driver to fan , bad mobo caused.

NO warranty answers by me.

View solution in original post

2 REPLIES 2
HP Recommended

HP fans are special, as are dells. , oem are.

first off the BIOS checks the fan  and runs it totally based on thermal demands.

the BIOS also has table showing the relation ship of PWM to RPM ( it sets PWM and if RPM is wrong bam errors)

if they do not match it warns you of  that. by DESIGN.

1:a dead fan.

2: fan is slow. due to lent packed or bearings bad, aka, a bad fan.

3: using non HP fans,

4: plugged in to wrong jack or indexed wrong (off center 1 pin not wired)

5:worse,  bad mobo driver to fan , bad mobo caused.

NO warranty answers by me.
HP Recommended

@Savvy2 Thank you very much.

† The opinions expressed above are the personal opinions of the authors, not of HP. By using this site, you accept the <a href="https://www8.hp.com/us/en/terms-of-use.html" class="udrlinesmall">Terms of Use</a> and <a href="/t5/custom/page/page-id/hp.rulespage" class="udrlinesmall"> Rules of Participation</a>.