На той же самой LTP-8X все проще
(config)# system fan
min-speed Set fan's rotation speed low limit
speed Set fixed/auto fan speed. Percent (15 - slowest, 100 - fastest, 'no fan
speed' - autospeed)
speed-level Set selected fan speed-level in speed-table
speed-table Set fan speed-table 15..100% 8 times