The unaccounted for fan is a Corsair A1225M12S. It's noise is 18.9 db(A). So now all mounted fans and the HDD are accounted for, it lands on 37.3 dB if the dB algorithm is correctly understood and implemented (start with the highest, then add 3 dB every time it is doubled).
So, that means only the GPU and the PSU are left! I did Google the GPU (GFX card) but I couldn't find anything, it is a msi Nvidia Geforce GT 710. As for the PSU, I must open the computer and have a look since I didn't write down anything except "Seasonic" ... See https://dataswamp.org/~incal/ebchw/COMPUTER fan connector fan mm pin dB(A) CHA_FAN1 Corsair A1225M12S 120 3 18.9 [2] CHA_FAN2 be quiet! Shadow Wings 2 140 4 14.9 CHA_FAN3 be quiet! Shadow Wings 2 140 3 14.7 [3] CPU_FAN be quiet! Pure Wings 2 120 4 15.9 [4] CPU_OPT be quiet! Pure Wings 2 120 4 15.9 (db 18.9 14.9 14.7 15.9 15.9) ; 28.6 dB mounted fans [5] (db 18.9 14.9 14.7 15.9 15.9 29) ; 37.3 dB mounted fans and HDD HDD $ sudo lshw -class disk # ATA Disk · SAMSUNG HD204UI · 2TB Samsung Spinpoint F4EG "Acoustics – Idle 2.5/2.6 Bel, Performance Seek 2.8/2.9 Bel" [6] [...] [2] https://archiwum.allegro.pl/oferta/wentylator-wentylator-corsair-a1225m12s-120mm-i7777314859.html [3] https://www.bequiet.com/en/casefans/1701 [4] https://www.bequiet.com/en/casefans/1626 [5] https://dataswamp.org/~incal/emacs-init/audio.el [6] https://www.storagereview.com/review/samsung-spinpoint-f4eg-review-hd204ui -- underground experts united https://dataswamp.org/~incal
