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- HP Community
- Desktops
- Desktop Boot and Lockup
- POST error 900 CPU fan not detected

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11-16-2017 11:11 AM
POST error the CPU fan is not detected. Then get 901 for rear fan and 902 for power supply. This is a brand new system. Opened her up and it is clean as a whistle (about 2 months old). shut it down and unplugged the connectors hit with an eraser, plugged them back in. Fans are running at FULL tilt. can install a controller if needed, but concerned that with a brand new PC already have issue.
Thanks!
11-17-2017 06:57 PM
> This is a brand new system. ... Fans are running at FULL tilt.
I presume that the warranty for your HP system is still valid.
Contact HP Support (hyperlink at the bottom-left of this web-page), to open an incident.
Fans *DO* run at 100%, until the motherboard detects that the computer's internal temperatures are not high-enough to justify spinning the fans at 100% -- the fans are told to "throttle-down" to a slower/quieter speed.
I think that you have a failing motherboard.
HP will replace it, under warranty.