Motherboard is an Asus Z87-C, CPU Intel i5 (Haswell).
I have been using Speedfan for years to monitor my computers without any issues of compatibility with the OS or hardware.
Unfortunately, Speedfan is not compatible with Windows 8.1 pro 64bit, I get a message saying so when I try to have Speedfan start when booting, however it starts without the compatibility message once Windows has started.
When Speedfan is running however, it does not show any information about the system fans' voltage or speed. Apparently it's due to recent Asus motherboards fan sensors being 'different' to all other motherboard designs (according to the Speedfan website)
The other problem is Speedfan is reporting incorrect CPU and motherboard temperatures.
The CPU and motherboard temperatures are showing as 5 - 10 degrees C BELOW the ambient room temperature. for example, Room teperature is 19C, Speedfan says the CPU temperature is 12C....

I have been trying various other system monitoring software all day, and most of them are not completely compatible with Windows 8.1 64bit, and/or have the same problem as Speed fan by reporting incorrect temperatures.
Anyone have any suggestions on their favourite system monitoring software? Preferably something that can run with a notifications icon, like Speedfan does.