I think it's because the Hyper 212 is tried and tested. Tonnes of reviews so there's a level of reassurance whereas we don't really have the data on FrostflowsBetween the CoolerMaster Hyper 212 (120mm) Fan CPU Cooler Black Edition & PCS FrostFlow 120 Series RGB High Performance Liquid Cooler (AMD).
Why do you rate the coolermaster above the frostflow? Does the liquid not provide better cooling?