Is this true from shuttles website
--Contrary to popular beliefs, the CPU, hard drive and mainboard temperatures are higher when the case is taken off of the XPC. Opening the case actually reduces the airflow through the case. The vents at the front of your XPC no longer take air in; therefore, the airflow around the PWM and MOSFET is significantly reduced. We recommend leaving the aluminum case closed on the XPC when in operation. This will improve the thermal dynamics of your XPC.
--Contrary to popular beliefs, the CPU, hard drive and mainboard temperatures are higher when the case is taken off of the XPC. Opening the case actually reduces the airflow through the case. The vents at the front of your XPC no longer take air in; therefore, the airflow around the PWM and MOSFET is significantly reduced. We recommend leaving the aluminum case closed on the XPC when in operation. This will improve the thermal dynamics of your XPC.