The 5.25" drive bay also doubles as part of something best described as a processor isolation chamber. Air is drawn in through the vents in the top of the case, through the removable air filter mounted to the top of the drive bay by the processor's fan, and then it exhausted out of the vents found above the rear I/O panel. This cooling arrangement is another point that reminds me of a BTX setup, as the processor fan doubles as the case cooling fan.



Link: BiGbruin