Your view of mechanical air replacement may be a tad jaundiced, perhaps from experience with clogged vents or the like? The SilenX IXP-34-08 Ixtrema fan that I have on the way is rated at 10cfm, or roughly 10 replacements of the internal air each minute. Even at half that throughput I suspect that few calories generated by the electronics will hang about for more than a moment, and the airflow's turbulence will prevent formation of any dead-spots anywhere inside the case.

Although the pudding has yet to be eaten—and I am prepared to experiment with directing the airstreams by judicious masking of the case vents—I have no fears about the outcome of forced ventilation. I am no stranger to airflow patterns, having spent four years at one time in the development of a method to produce high-activity dry yeast from compressed yeast, using air-lift dryers.

de