it87 module won't load

Try typing:

sudo modprobe i

Then press TAB a few times. It should autocomplete the name. It may give clues

sudo modprobe i
just gives:

im-config irqbalance

on pressing tab

What is the output of

uname -a
modinfo it87
modinfo /lib/modules/3.13.0-37-generic/kernel/drivers/hwmon/it87.ko
sudo modprobe --verbose it87

You might also try
sudo sensors-detect
(beware of the warning in http://manpages.ubuntu.com/manpages/trusty/en/man8/sensors-detect.8.html )

Output is:-

uname -a
Linux infinity 3.13.0-37-generic #64-Ubuntu SMP Mon Sep 22 21:28:38 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

modinfo it87
filename: /lib/modules/3.13.0-37-generic/kernel/drivers/hwmon/it87.ko
license: GPL
description: IT8705F/IT871xF/IT872xF hardware monitoring driver
author: Chris Gauthron, Jean Delvare <email address hidden>
srcversion: 21235576BE7B439B25C57A5
depends: hwmon-vid
intree: Y
vermagic: 3.13.0-37-generic SMP mod_unload modversions
signer: Magrathea: Glacier signing key
sig_key: 2C:B1:13:3B:35:F9:5A:9E:24:DE:AB:EE:B1:2B:A4:49:BC:BA:BB:C9
sig_hashalgo: sha512
parm: force_id:Override the detected device ID (ushort)
parm: update_vbat:Update vbat if set else return powerup value (bool)
parm: fix_pwm_polarity:Force PWM polarity to active high (DANGEROUS) (bool)

modinfo /lib/modules/3.13.0-37-generic/kernel/drivers/hwmon/it87.ko
filename: /lib/modules/3.13.0-37-generic/kernel/drivers/hwmon/it87.ko
license: GPL
description: IT8705F/IT871xF/IT872xF hardware monitoring driver
author: Chris Gauthron, Jean Delvare <email address hidden>
srcversion: 21235576BE7B439B25C57A5
depends: hwmon-vid
intree: Y
vermagic: 3.13.0-37-generic SMP mod_unload modversions
signer: Magrathea: Glacier signing key
sig_key: 2C:B1:13:3B:35:F9:5A:9E:24:DE:AB:EE:B1:2B:A4:49:BC:BA:BB:C9
sig_hashalgo: sha512
parm: force_id:Override the detected device ID (ushort)
parm: update_vbat:Update vbat if set else return powerup value (bool)
parm: fix_pwm_polarity:Force PWM polarity to active high (DANGEROUS) (bool)

sudo modprobe --verbose it87
insmod /lib/modules/3.13.0-37-generic/kernel/drivers/hwmon/it87.ko
modprobe: ERROR: could not insert 'it87': No such device

sensors-detect says it detects a chip of the ITE family.

OK. It seems to me that the error message of the modprobe tries to tell, that it does not find any device that is compatible to the it87 kernel module.

You might need to add
force_id= (the ID for your sensor)
to the modprobe command.

No idea how to correctly identify the required ID, does the sensors-detect command provide details about the chip?

The relevant part of the sensors-detect output is:-

Probing for Super-I/O at 0x2e/0x2f
Trying family `National Semiconductor/ITE'... No
Trying family `SMSC'... No
Trying family `VIA/Winbond/Nuvoton/Fintek'... No
Trying family `ITE'... Yes
Found unknown chip with ID 0x8620

Presumably the ID is 0x8620

But I can't actually see "force_id" in the modprobe manpage. What exactly would the syntax be?

The parameters that can be added to a module with the modprobe command are module dependent, so you will not find details in the man pages. The output of the "modinfo <modulename>" command list the possible parameters for a module (see your output above)

I would try
sudo modprobe --verbose force_id=0x8620
or of that fails or does not work maybe
sudo modprobe --verbose force_id=0x8728
see also http://lm-sensors.org/wiki/Devices (search for 8620)

sudo modprobe --verbose it87 force_id=0x8620 worked

I can now see the fan speed.

Many thanks for your help.