Hardware monitor showing impossable readings.

[Computer_Commando]

according to speedfan my +12V rail is only 1.09V ,my -12V rail is -16V, and my -5V is -8V. Each of these is well outside the tolerance of a PWR_GOOD signal, and if they were accurate I doubt it would have run for the last four years with these readings.
...or (usually more likely) software that doesn't know where to look for the values on that motherboard. Usually it takes a quick look around and makes assumptions about where things are. Sometimes  those assumptions are wrong and will give you silly values...

It's all in the software as BC_P states.
I no longer use or trust SpeedFan anymore, e.g. +12V = 2.82-3.01V
It may be accurate for an older computer or motherboard, but it's rarely updated more than once a year.  This computer is about 2-3 years old.
www.hwinfo.com is now the best and is continuously being updated.

[Salmon Trout]

(Speedfan)

It may be accurate for an older computer or motherboard,

Works fine on my brand new Shuttle SZ68R5. All voltages seem accurate, fan control is working OK and temperatures match readings of other apps.

but it's rarely updated more than once a year.

4.47 is still in beta (Beta 2 May 5, 2012)

regular releases

4.46 March 27, 2012
4.45 November 3, 2011
4.44 July 13, 2011
4.43 March 17, 2011
4.42 November 3, 2010
4.41 July 24, 2010
4.40 November 28, 2009
4.39 August 09, 2009
4.38 April 22, 2009
4.37 November 21, 2008

the pattern is consistent further back