Huh? I think that isn't quite right. Unrestricted airflow is better. The fans are mostly for the cpu and the gpu. Those have heat sinks on them that are connected to cooling fins. You want as much air to hit those fins as possible. The heat is then transfered to the air, which is being blown out. Hope that makes sense. But be careful enlarging the grill. First it probably violates your warranty. Second if the holes are too big, then things can get in. Like paper clips, food, fingers, etc. These might damage the fans. I wouldn't recomend doing it. Instead clean dust out so air is flowing good. If temps are still higher then when new, then maybe repaste. Not all models are easy to get to the cpu and gpu to repaste. But if you have access, then it is fairly easy.