Ubuntu does not put CPU into idle state

[Kaspar Tint]

When booting into Windows partition, it manages to downclock and lower the V-core of my Intel i5-4570 CPU. This gives me a steady 25 C temperature during idle time. (measured with physical device and measured with Windows application called SpeedFan).

On Ubuntu, this does not seem to happen. Even if I do echo "ondemand" | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor , the CPU temperature is still about 40 C high during idle time.
I do this measurement after clean boot, CPU usage is 0-6% and temp is 40 C steady.
I use xsensors to look at my CPU temps and frequencies.

This means that Ubuntu does not effectively downclock and lower the V-core of CPU when computer is in a idle state. I belive this is true to any version of Ubuntu now as I can see the effect on my Laptops that are using Ubuntu also. The battery life is much shorter than it is with Windows running on them.

I have made my tests with a desktop computer using:

CPU: i5-4570
GPU: GTX 760
Mobo: Asus B85-Plus
OS: Ubuntu 14.04 64 bit

Also made tests on various Lenovo thinkpads and Ultrabooks. Results remain the same, Ubuntu makes the CPU a lot hotter because of the reasons I posted.