The Lian Li PC-75 Black utilizes its 4 80mm to cool an entire case. They get the job done but wouldn't it be nice to run all 4 on low, so the case is silent? With this side panel with a mesh ventilation grill, you won't have to hear your case make more than a whisper ever again. With side panel ventilation from this Lian Li PC-75 Side Panel, your case will be cooler than ever before without the noise. It even provides a unique look to your window that will set it apart from all the other Lian Li PC-75 Cases.