TBH on mine I placed them on the rear of the mobo - 1 each at bottom rear, top rear, bottom front, top front. Although they are not actually measuring individual components they do give a very good indication of case temps within each 'zone' of the rig, and in combination with apps like Realtemp and GPU-Z you can quickly get a feel for how the case temps (and ambient) can affect actual components temps. I also did this as I wanted my case to be as clear of cabling etc as possible.