As my computer runs a bit hot I decided to purchase some case fans. I bought some cheap ones off ebay but they didn't provide the necessary airflow so I turned to Quietpc and bought some Acoustifans. The airflow's a lot better but they make a high pitched whining noise which they shouldn't. The cause for this noise is the holes in my case which the air flows through. If I put my hand over the holes the noise stops, so it's not the fans spining that's causing it. Anyway I just wondered if anyone can provide a, preferably easy, solution to this case grill problem so I can go back to having a quiet pc.