Interapplication interference at shared main memory slows down different applications differently. A few slowdown estimation models have been proposed to provide predictable performance by quantifying memory interference, but they have relatively low accuracy. Thus, we propose a more accurate slowdown estimation model called SEM at main memory. First, SEM unifies the slowdown estimation model by measuring IPC directly. Second, SEM uses the per-bank structure to monitor memory interference and improves estimation accuracy by considering write interference, row-buffer interference, and data bus interference. The evaluation results show that SEM has significantly lower slowdown estimation error (4.06%) compared to STFM (30.15%) and MISE (10.1%).