I thought the heatsink test procedure
on SPCR was open bench?
If so there isn't a normal airflow and every case+casefans combination changes those temps.
It has also been argued that the platform should be enclosed to simulate in-system conditions. If so, other considerations have to be made. What type of enclosure? One with the power supply at the bottom or top? Where should the fan placements and ventilation points be located and what size? Should we add a system fan, and if so, which one, and set at what speed? Going this route may lead to realistic results, but for only one case layout. Also, any extra variables we introduce would benefit some heatsinks while being a detriment to others. For a fair test of heatsink efficiency, we need to eliminate as many performance-affecting variables as possible. For isolating the heatsink, our original, open system setup seems optimal.