USB fan for cooling inside rack?

This is my first post here and I didn't find an answer by searching, so I'm asking. Has anyone tried using a small USB powered fan(plugged into front panel of KPR) to keep it cool inside. Wondering if Kemper says it's an ok idea. Any issues in doing this like noise, etc? My Gator padded rack is pretty insulated and the KPR gets warm and I don't want any unnecessary shutdowns.