I have a dell optiplex 9020 that has an unusual problem. The unit works fine, powering on and running normally. No issue with stability and performs as expected. However, as soon as power is applied to the unit (i.e. power cable plugged in) the fans spool up to full power. The fans remain on 100% until the power button is pressed, following which they spin down and act normally. I have updated all drivers and bios, tried disabling C-states and changing any remoterly appropriate bios options. Anyone got any ideas?
it's something that keeps the car engine running to allow the turbo time to cool down properly, avoiding damage. - linky: https://en.wikipedia.org/wiki/Turbo_timer In a pc context some PCs/PSUs keep the fans spinning for a few minutes after the pc shuts down to aid cooling.
Are the fans hooked directly to the PSU or to the board? If former then if the PSU sends out power regardless of motherboard, that'll be the reason.
bios setting have been fiddled with but a jumper is a new angle! Will see if I can get the usff 9020 motherboard layout and see if a jumper needs tweaking!
The Bios for the 9020 has a setting called 'Fan Control Override', which if enabled, cases the fans to go at full tilt all of the time. It's in the 'Power Management' section. ...source - R-ing TFM [Page 37]
Tried that. It only impacts when the PC is turned on. It just makes the board sound the same when powered on and off.
Similar-ish thread here discussing 100% fans and blaming the Master I/O board. Various jumper resets and firmwares as recommended fixes. https://www.dell.com/community/Desktops-General-Read-Only/XPS-730-FANS-AT-100/td-p/3029889