It should be lowering in temperature when lowering frequency and voltage. See how the min Frequency is 1596MHz (1600MHz) , while idling Ivy bridge is known cool down well enough. I'd say your target should be 25°C for min temps.
What is the voltage range with your CPU? it should be roughly 0.875v for Idle at 0-1% load.
You may ahve to navigate your way around the UEFI BIOS of your Motherboard. But first check and make sure that the Windows Power options is set to Balanced , not high performance. You can adjust later.