Idle Temp: This is when you're not stressing your CPU with a PC game or application, so just using Windows. This temp will be based on the ambient temperature in your room, but you should expect ...
meaning they're not useful if you're interested in reading the CPU temperature while you’re actually using Windows, such as when playing a game that can cause the processor to heat up.
In both cases, there has been some very small improvement in CPU temperatures. [Luumi] says part of the problem is his water cooling block is not completely flat and needs to be lapped.