Do the series 8 PCH (Z87, Q87 etc) really need a heatsink? I can see the PCH temperature in Intel Desktop Utilities never exceeding 50 degrees and they are rated up to 104 degrees (Celsius). However the SIO temperature is varying between 50-60 degrees and has no heatsink attached, even though it can work well up to 78 degrees.
The answer is yes, the 8 Series PCH requires a heatsink. It is this heatsink that is keeping the temperature in the range it is. Your temperature readings are lower than what I am seeing (but I test with mostly pre-production boards)...