Gelid Solutions Silent5 50X50X15Mm Silent Case Fan. SILENT 5. Featuring Silent Operation, Optimized Fan Blades, High Airflow & High Static Pressure, Long Lifetime (50'000 h MTTF at 40aC), 3 Years Warranty. The Silent 5 (FN-SX05-40) 50mm Silent Case Fan is designed for Silent enthusiasts GELID Silent case fans provide additional airflow without increasing noise levels and at affordable prices. Precisely balanced fan blades and long life Hydro Dynamic bearing guarantee ultra low noise.