I'm using Ubuntu 12.04 LTS. I'm not sure if it is the CPU (i7) fan or the video card fan.

I've tried using lm-sensors & fancontrol

sudo sensors-detect

Now follows a summary of the probes I have just done.
Just press ENTER to continue: 

Driver `w83627ehf':
  * ISA bus, address 0x290
    Chip `Nuvoton NCT6776F Super IO Sensors' (confidence: 9)

Driver `coretemp':
  * Chip `Intel digital thermal sensor' (confidence: 9)

To load everything that is needed, add this to /etc/modules:
# Chip drivers
coretemp  
w83627ehf

Like many people, I'm also getting error:

/usr/sbin/pwmconfig: There are no pwm-capable sensor modules installed  

Here is the output of sensors:

# sensors
radeon-pci-0100
Adapter: PCI adapter
temp1:        +71.0°C  

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +44.0°C  (high = +80.0°C, crit = +98.0°C)
Core 0:         +44.0°C  (high = +80.0°C, crit = +98.0°C)
Core 1:         +40.0°C  (high = +80.0°C, crit = +98.0°C)
Core 2:         +43.0°C  (high = +80.0°C, crit = +98.0°C)
Core 3:         +42.0°C  (high = +80.0°C, crit = +98.0°C)

I'm hoping some-one has already solved this for my configuration because this seems to be a problem for many people and there are many different suggestions.