From 0ead31aaf176ad54d10fbf396d8d01d374e1c37e Mon Sep 17 00:00:00 2001 From: "Mark D. Studebaker" Date: Sat, 8 Jan 2000 03:42:38 +0000 Subject: [PATCH] (mds) Some helpful hints on setting fan divisors. I always forget whether to increase or decrease so I figured it out and wrote it down. git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@685 7894878c-1315-0410-8ee3-d5d059ff63e0 --- doc/fan-divisors | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 doc/fan-divisors diff --git a/doc/fan-divisors b/doc/fan-divisors new file mode 100644 index 00000000..a493e04c --- /dev/null +++ b/doc/fan-divisors @@ -0,0 +1,37 @@ +If you aren't getting the expected readings on your fans, +try the following: + +- Do you get a fan reading in the BIOS or in DOS? + If not, you may not have a fan with a tachometer output. + Look and see. Fans with tachometer outputs have THREE wires. + +- Try experimenting with the fan divisor settings: + + +Fan Divisor Minimum RPM Maximum RPM + + 1 5314 1350000 + 2 2657 675000 + 4 1328 337500 + 8 664 168750 + 16 332 84375 + 32 166 42187 + 64 83 21093 +128 41 10546 + + +Pick a divisor so that the nominal RPM is about 50% +above the minimum. This is a good compromise between +margin and accuracy. + +If you have a 0 RPM reading some or all of the time, +increase the divisor until you get good readings. + +If you have a nominal reading less than 1.25 times the +minimum, increase the divisor to give you margin +so that you will not get spurious alarms. + +If you have a nominal reading more than 3 times the +minimum, decrease the divisor to provide better +accuracy. +